Publications

Conference Proceedings

2021

Dehner, C. ; Olefir, I. ; Basak, K. ; Jüstel, D. ; Ntziachristos, V.
In: (2021 European Conferences on Biomedical Optics, ECBO 2021, 20-24 June 2021, Virtual, Online). 2021.:ES1C.1 (Optics InfoBase Conference Papers)
Image contrast in multispectral optoacoustic tomography can be reduced by electrical noise. We present a deep learning method to remove electrical noise from optoacoustic signals and thereby significantly enhance morphological and spectral contrast.
Dehner, C. ; Olefir, I. ; Basak, K. ; Jüstel, D. ; Ntziachristos, V.
In: (European Conference on Biomedical Optics, 20–24 June 2021, Munich Germany). 2021. DOI: 10.1117/12.2614318 ( ; 11923)
Image contrast in multispectral optoacoustic tomography can be reduced by electrical noise. We present a deep learning method to remove electrical noise from optoacoustic signals and thereby significantly enhance morphological and spectral contrast.
Jüstel, D. ; Basak, K. ; Bader, M. ; Dehner, C. ; Ntziachristos, V.
In: (European Conference on Biomedical Optics 2021, 20–24 June 2021, Munich, Germany). 2021.
The total impulse response of a clinical optoacoustic system is characterized by combining experimentally acquired signals with a numerical model of the spatial impulse response, resulting in high-resolution images in clinical applications.
Liu, N. ; O'Connor, P. ; Gujrati, V. ; Gorpas, D. ; Glasl, S. ; Blutke, A. ; Walch, A.K. ; Kleigrewe, K.* ; Sattler, M. ; Plettenburg, O. ; Ntziachristos, V.
In: (European Conference on Biomedical Optics, 20–24 June 2021, Munich Germany). 2021. DOI: 10.1117/12.2615998 ( ; 11923)
CR760, a croconaine dye with excellent optical properties, was synthesized in a single step and subsequently nano-formulated for optoacoustic imaging and photothermal therapy of cancer.
Pieters, C.* ; Westerveld, W.J.* ; Mahmud-Ul-Hasan, M.* ; Severi, S.* ; Shnaiderman, R. ; Ntziachristos, V. ; Billen, M.* ; Kjellman, J.* ; Jansen, R.* ; Rochus, V.* ; Rottenberg, X.*
In: (European Conference on Biomedical Optics 2021, 20–24 June 2021, Munich, Germany). 2021.
We propose a new opto-mechanical ultrasound sensor (OMUS) enabled by an innovative silicon photonics waveguide. We present experimental results up to 30 MHz, a 10-sensor array proof-of-concept and our latest findings.
Subochev, P.* ; Deán-Ben, X.L.* ; Chen, Z.* ; Orlova, A.* ; Razansky, D.
In: (European Conferences on Biomedical Optics 2021, 20–24 June 2021, Munich, Germany). 2021.
We developed high-density spherical matrix array based on polyvinylidene difluoride films. Ultrawide bandwidth (0.3-38 MHz) and sub-millimeter sized elements enabled non-invasive cerebrovascular imaging of adult mouse with ~60 µm resolution.

2020

2019

Seyedebrahimi, M.M. ; Pleitez, M.A. ; Mohajerani, P. ; Ntziachristos, V.
In: (European Conferences on Biomedical Optics, Munich, Germany). 2019. (Proc. SPIE ; 11077)
In this work we developed a novel near-infrared two-path optoacoustic spectrometer (NiR-TAOS) that could sense OA intensity changes due to metabolite concentration changes in-vivo. The main aim of dividing the optical path in two is 1) perform real time correction of the laser emission profile of the laser source at different wavelengths and, 2) perform pulse to pulse correction to remove laser beam fluctuation and instability to increase signal to noise ratio. Signal to noise ratio improvement was significant not only at spectral peaks, but also at all other wavelengths. The system can be used for broad applications in biomedical measurements such as various metabolites in the SWIR.

2018

Estrada, H. ; Gottschalk, S. ; Reiss, M. ; Neuschmelting, V.* ; Rebling, J. ; Goldbrunner, R.* ; Razansky, D.
In: (IEEE International Ultrasonics Symposium, IUS 2018, 22-25 October 2018, Kobe; Japan). 2018.:8580113
Current knowledge on the ultrasound wave propagation in the cranial bone is restricted to far-field observations. In order to extend our understanding on how ultrasound waves propagate in the skull, we use short laser pulses to excite ultrasound waves in water-immersed ex vivo mouse and human skulls and explored their near-field. The laser pulses (10 ns duration) of 532 nm are absorbed by a small layer of black burnish deposited on the skull's inner surface and generate ultrasound waves due to the thermoelastic effect. The acoustic near-field is mapped using a needle hydrophone close to the skull surface, following a three-dimensional scanning path derived from a previous pulse-echo scan of the skull with a spherically focused ultrasound transducer. The results for mouse and human skulls show different wave propagation regimes according to their differences in size, thickness, and internal structure. Leaky and non-leaky waves have been observed for both skull samples. Zero order Lamb modes were observed in the mouse skull, whereas Rayleigh-Lamb higher order modes can be observed in the human skull sample, presumably propagating in the outer cortical bone layer. Good agreement is found between the experiments and the multilayered flat plate model.

2017

Dean-Ben, X.L. ; Gottschalk, S. ; Sela, G. ; Shoham, S.* ; Razansky, D.
In: (Conference Proceedings, Optics and the Brain 2017, Optics in the Life Sciences Congress, 2–5 April 2017, San Diego, California United States). 2017. ( ; Part F76-BRAIN 2017)
Calcium transients in the brain of adult zebrafish expressing GCaMP5G were monitored with optoacoustic tomography. Optoacoustics can visualize neural activity at penetration depths and spatio-temporal scales not covered with the existing modalities.
Ding, L ; Dean-Ben, X.L. ; Razansky, D.
In: (SPIE Photonics West, 28 January-02 February 2017, San Francisco, CA, USA). 2017.:100641A ( ; 10064)
In order to achieve real-time image rendering, optoacoustic tomography reconstructions are commonly done with back-projection algorithms due to their simplicity and low computational complexity. However, model-based algorithms have been shown to attain more accurate reconstruction performance due to their ability to model arbitrary detection geometries, transducer shapes and other experimental factors. The high computational complexity of the model-based schemes makes it challenging to be implemented for real time inversion. Herein, we introduce a novel discretization method for model-based optoacoustic tomography that enables its efficient parallel implementation on graphics processing units with extremely low memory overhead. We demonstrate that, when employing a tomographic scanner with 256 detectors, the new method achieves model-based optoacoustic inversion at 20 frames per second for a 200 × 200 image grid.
Gottschalk, S. ; Dean-Ben, X.L. ; Shoham, S.* ; Razansky, D.
In: (Conference Proceedings, Optics and the Brain 2017, Optics in the Life Sciences Congress, 2–5 April 2017, San Diego, California United States). 2017. ( ; Part F76-BRAIN 2017)
Genetically encoded calcium indicators are powerful brain activity-sensors. Here, we demonstrate noninvasive volumetric optoacoustic neuroimaging of rapid calcium transients in living GCaMP6f-expressing mice exposed to electrical hindpaw stimulation.
Gottschalk, S. ; Fehm, T. ; Dean-Ben, X.L. ; Tsytsarev, V.* ; Razansky, D.
In: (Conference Proceedings, Optics and the Brain 2017, Optics in the Life Sciences Congress, 2–5 April 2017, San Diego, California United States). 2017. ( ; Part F76-BRAIN 2017)
Thalamocortical activity in epilepsy was studied in mice using an optoacoustic functional neuroimaging framework correlating hemodynamic responses with concurrent EEG-readings, demonstrating noninvasive real-time visualization of deep epileptic foci.
Ntziachristos, V.
In: Part F82-CLEO_Europe 2017 (The European Conference on Lasers and Electro-Optics, CLEO_Europe 2017, 25-29 June 2017, Munich; Germany). 2017. (Optics InfoBase Conference Papers)

2016

Aguirre Bueno, J. ; Schwarz, M. ; Ntziachristos, V.
In: Part F19-Translational 2016 (Clinical and Translational Biophotonics, Translational 2016, 25–28 April 2016, Fort Lauderdale, Florida United States). 2016. 3 S. (Optics InfoBase Conference Papers)
We have further developed the skin imaging optoacoustic mesoscopy technology building the first broadband, high frequency, raster scan handheld system. The apparatus is designed to provide cross sectional images that contain rich depth dependent information. A compact fixed illumination scheme fulfills the imaging and size demands of the scanner. The system capabilities haves been characterized using experiments with phantoms and healthy subjects.
Dean-Ben, X.L. ; Stiel, A.-C. ; Jiang, Y. ; Razansky, D.
In: (Optical Tomography and Spectroscopy). 2016.
We report on a new method for mapping light fluence distribution deep in a scattering tissues based on real-time optoacoustic tomographic acquisition of temporal data from reversibly switchable fluorescent proteins (RSFPs).
Ding, L ; Dean-Ben, X.L. ; Razansky, D.
In: Optical Tomography and Spectroscopy 2016 (Clinical and Translational Biophotonics, Translational 2016, 25-28 April 2016, Fort Lauderdale, Florida United States). 2016. 3 S. (Optics InfoBase Conference Papers)
We describe a novel discretization procedure for model-based inversion in twodimensional optoacoustic tomography. This procedure can be efficiently implemented on a graphic-processing-unit and enables model-based image reconstruction at a frame rate exceeding 10 Hz.
Viswanath, P.S.* ; Weiser, T.* ; Chintala, P.* ; Mandal, S. ; Dutta, R.
In: (3rd IEEE EMBS International Conference on Biomedical and Health Informatics, 24-27 February 2016, Las Vegas, USA). 2016. 172-175
Visual observation of Cumulus Oocyte Complexes provides only limited information about its functional competence, whereas the molecular evaluations methods are cumbersome or costly. Image analysis of mammalian oocytes can provide attractive alternative to address this challenge. However, it is complex, given the huge number of oocytes under inspection, subjective nature of the features inspected for identification. Supervised machine learning methods like random forest with annotations from expert biologists can make the analysis task standardized and reduces inter-subject variability. We present a semiautomatic framework for predicting the class an oocyte belongs to, based on multi-object parametric segmentation on the acquired microscopic image followed by a feature based classification using random forests.

2015

Garcia-Allende, P. ; Koch, M. ; Glatz, J. ; Symvoulidis, P. ; Ntziachristos, V.
In: Proceedings (Optical Molecular Probes, Imaging and Drug Delivery, OMP 2015, 12-15 April 2015, Vancouver, Canada). 2015.
Wide-field targeted fluorescence evolves as a promising approach for interventional guidance. We present an overview of the key developments from our laboratory and discuss their potential to shift the surgical and endoscopic imaging paradigm.
Ghosh, S.* ; Samineni, A.* ; Mandal, S. ; Murari, B.M.*
In: (37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2015, 25-29 August 2015, Milan, Italy). 2015. 3647-3650 (Conf. Proc. IEEE Eng. Med. Biol. Soc. ; 2015)
A student chapter can be considered to be a miniature enterprise; however without the latter's major financial risks. Involvement in the student chapter of a professional society like IEEE at undergraduate level plays a pivotal role in the overall professional development of the student by keeping the students informed about the various career possibilities. A student chapter shapes the hitherto naive students into industry ready professionals and to suitable candidates for some of the best grad schools worldwide. This assertion has been discussed in-depth taking the example of IEEE EMBS Student Branch chapter of VIT University. It has been described how the entire process, - starting from inception of an idea to its materialization in to an activity, has shaped the volunteers and participants into better professionals.
Wissenschaftlicher Artikel
Scientific Article
Gottschalk, S. ; Fehm, T.* ; Dean-Ben, X.L.* ; Razansky, D.
In: (7th International IEEE/EMBS Conference on Neural Engineering (NER), 2015, 22-24 April 2015). 2015.
We present a technique for fully noninvasive acquisition of real-time volumetric multispectral optoacoustic data from whole mouse brain. The neuroimaging capacity of the new methodology is demonstrated here by simultaneous label-free assessment of multiple stimulus-evoked hemodynamic responses, including blood oxygenation, total hemoglobin, cerebral blood volume, oxygenized and deoxygenized hemoglobin.
Gracia-Allende, P.B. ; Koch, M. ; Glatz, J. ; Symvoulidis, P. ; Ntziachristos, V.
In: (Proceedings Optical Molecular Probes, Imaging and Drug Delivery, OMP 2015, 12-15 April 2015, Vancouver; Canada). 2015.
Wide-field targeted fluorescence evolves as a promising approach for interventional guidance. We present an overview of the key developments from our laboratory and discuss their potential to shift the surgical and endoscopic imaging paradigm.
Ho, C.J.H.* ; Burton, N.C. ; Morscher, S. ; Dinish, U.S.* ; Reber, J. ; Ntziachristos, V. ; Olivo, M.*
In: (Frontiers in Biophotonics for Translational Medicine : In the Celebration of Year of Light). Singapore: Springer Science+Business Media, 2015. 75-109 (Prog. Opt. Sci. Photonics ; 3)
Optoacoustic imaging has been widely used for in vivo disease diagnosis and therapy monitoring. Acquisition hardware, analysis, and contrast agents have been subject to much innovation, creating access to an ever-growing range of biomedical applications. In this review, a broad overview of optoacoustic theory, instrumentation and data processing is provided, together with the various categories of contrast agents that have been developed. In addition, the application of these techniques and contrast agents in preclinical and clinical imaging applications will be discussed in detail, ranging from imaging of cancer and various organs like skin, brain and breast to sentinel lymph node mapping. Finally under conclusions, we highlighted future perspectives in this field, in the context of instrumentation and software development, as well as advances in clinical translation.
Mandal, S. ; Viswanath, P.S.* ; Yeshaswini, N.* ; Dean-Ben, X.L. ; Razansky, D.
In: (37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2015, 25-29 August 2015, Milan, Italy). 2015. 707-710 (Conf. Proc. IEEE Eng. Med. Biol. Soc.)
In this article, we present a novel scheme for segmenting the image boundary (with the background) in optoacoustic small animal in vivo imaging systems. The method utilizes a multiscale edge detection algorithm to generate a binary edge map. A scale dependent morphological operation is employed to clean spurious edges. Thereafter, an ellipse is fitted to the edge map through constrained parametric transformations and iterative goodness of fit calculations. The method delimits the tissue edges through the curve fitting model, which has shown high levels of accuracy. Thus, this method enables segmentation of optoacoutic images with minimal human intervention, by eliminating need of scale selection for multiscale processing and seed point determination for contour mapping.
Mohajerani, P. ; Meier, R.* ; Rummeny, E.J.* ; Ntziachristos, V.
In: (2nd International Conference on Bioimaging, BIOIMAGING 201, 12-15 January 2015, Lisbon; Portugal). 2015. 36-43
Successful detection of rheumatoid arthritis (RA) at the early stages of development can significantly enhance the chances of effective therapy. The early onset of RA is often marked with inflammation of the synovial lining of the joint, a condition known as synovitis. Effective imaging of synovitis is therefore of critical importance. While dynamic, contrast-enhanced magnetic resonance imaging (MRI) is capable of effective imaging of synovitis, it is a costly modality. As an alternative, inexpensive approach, optical imaging post injection of the near-infrared fluorescent dye indocynine green (ICG) has been recently proposed for imaging RA. Evaluation of the obtained optical images is performed via examination by trained human readers. However, optical imaging has yet to achieve the diagnostic accuracy of MRI. In this paper we present a method for automatic evaluation of the fluorescence images and compare its performance with the human-based evaluation. Our method relies on our previous work on spatiotemporal analysis of image sequence with principal component analysis (PCA) to seek synovitis signal components with the help of a segmentation method. The results for a group of 600 joints, obtained from 20 patients, suggest improved diagnostic performance using the automatic approach in comparison to human-based evaluation.
Ntziachristos, V. ; Rosenthal, A.
In: (12th IEEE International Symposium on Biomedical Imaging, 16-19 April 2015, Brooklyn; United States). 2015. 1228-1231
One of the challenges of multispectral optoacoustic tomography (MSOT) is the reconstruction of the images from the projection data. Conventionally, analytical inversion formulae are used owing to their simplicity and numerical efficiency. However, such solutions are often limited to ideal detection scenarios and lead to image artifacts when the system characteristics deviate from the assumed ones. In such cases, image quality may be improved by adopting a model-based approach in which the MSOT system is modeled via a matrix relation, which is subsequently inverted using established algebraic techniques to reconstruct the image. Nonetheless, model-based inversion is usually more computationally demanding than its analytical counterparts owing to the large size of the model matrix. In this paper, we analyze the sparsity that exists in the model matrix and show how it may be exploited for accelerating image reconstruction. In particular, a wavelet-packet framework is presented under which the size of the model matrix may be reduced.

2014

Mandal, S. ; Usop, K.* ; Ong, R.* ; Gonzalez, E.A.* ; Reilly, R.*
In: (Global Engineering Education Conference (EDUCON), 2014 IEEE, 3-5 April 2014). 2014.
Most of the developing countries, suffer from an intrinsic and extrinsic divide between the classroom education and its practical implementation for societal well-being. In a new program termed as 'IEEE Direct to Students'(D2S) we try to lessen the gap by involving college and high school students, and young professionals. D2S aims to empower rural and urban informal sector youth to address district problems via frugal engineering innovations. The first pilot of the program was done in Philippines through seminar and awareness lectures, handson projects and exhibitions, and will be rolled out in newer geographies based on the initial observations of the pilot study.
Mirapeix, J.M.* ; Cobo, A.* ; Valdiande, J.J.* ; Ruiz-Lombera, R.* ; Garcia-Allende, P. ; Conde, O.M.* ; Rodriguez-Cobo, L.* ; Lopez-Higuera, J.M.*
In: Proceedings (20th IMEKO TC4 Symposium on Measurements of Electrical Quantities: Research on Electrical and Electronic Measurement for the Economic Upturn, Together with 18th TC4 International Workshop on ADC and DCA Modeling and Testing, IWADC 2014, 15.- 17. September 2014, Sannio Beneveto, Italy). 2014. 189-194
A review of solutions involving plasma optical spectroscopy applied to on-line welding quality monitoring is presented in this paper. After a brief introduction to welding processes and their requirements in terms of quality monitoring, different proposals for on-line monitoring will be addressed. The basics of welding monitoring via plasma spectroscopy in terms of light capture and hardware and processing requirements will be also introduced, and different approaches will be presented. Finally, a variety of examples regarding field trials in different sectors will be also discussed.
Mulrenin, R.* ; Strohmeier, F.* ; Kabak, Y.* ; Pabst, A.* ; Demski, H. ; Lamprinos, I.*
In: Proceedings (eChallenges e-2014 Conference, 29 - 31 October 2014, Belfast, Nothern Ireland). Belfast: IEEE, 2014. 1-8
Symvoulidis, P. ; Cruz Perez, C. ; Schwaiger, M.* ; Ntziachristos, V. ; Westmeyer, G.G.
In: Proceedings (IEEE International Symposium on Biomedical Imaging, ISBI, 29. April - 02.May 2014, Beijing, China). IEEE: Piscataway, NJ, 2014. 890-893
Serial sectioning combined with microscopy provides high resolution volumetric data to complement in-vivo imaging modalities and aid ex-vivo diagnostics. We describe the design of a fully-automated cryomicrotome combined with a multispectral reflection and fluorescence imaging system that enables high-throughput analyses of biological specimens with a large field of view and cellular resolution while keeping the manufacturing and running costs low. We show the performance of the system for representative applications in high-resolution volumetric imaging of reporter animals and multispectral tissue analysis. Furthermore, we demonstrate the versatility of the economical imaging system in applications such as in vivo epifluorescence imaging, histology slide scanning, cell counting and gel electrophoresis documentation.

2013

Bay, E. ; Douplik, A.* ; Razansky, D.
In: Oraevksy, A.A.* ; Wang, L.V.* [Eds.]: SPIE Photons Plus Ultrasound: Imaging and Sensing 2013 (Conference Photons Plus Ultrasound: Imaging and Sensing, San Francisco USA, 3-5 February 2013). Washington, USA: Society of Photo-Optical Instrumentation Engineers, 2013.:85813X (Proc. SPIE ; 8581)
Laser-tissue interaction during laser surgery can be classified into two biophysical processes: tissue removal in the focal zone of the laser beam and heating in the surrounding tissue. In order to ensure a precise cut and minimal collateral thermal damage, the surgeon has to control several parameters, such as power, repetition rate and fiber movement velocity. In this study we propose utilizing optoacoustics for providing the necessary real-time feedback of cutting and heating processes. A single Q-switched Nd-YAG laser (532nm, 4 KHz, 18 W, pulse duration 7.6ns) was used for ablation and generation of optoacoustic signals in fresh bovine tissue samples. Both shockwaves, generated due to tissue removal, as well as normal optoacoustic responses from the surrounding tissue were detected using a single 10MHz piezoelectric transducer. It has been observed that rapid reduction in the shockwave amplitude occurs as more material is being removed from the focal zone, indicating decrease in cutting efficiency of the laser beam, whereas gradual decrease in the optoacoustic signal likely corresponds to coagulation around the ablation crater. Further heating of surrounding tissue leads to carbonization accompanied by a significant shift of spectral components of the optoacoustic signal. Our results hold promise for real-time monitoring of cutting efficiency and collateral thermal damage during laser surgery.
Conde, O.M.* ; Eguizabal, A.* ; Real, E.* ; Lopez-Higuera, J.M.* ; Garcia-Allende, P. ; Cubillas, A.M.*
In: Proceedings of the ICAIT 2013 (6th International Conference on Advanced Infocomm Technology, 6 - 9 July 2013, Hsinchu). Piscataway, NJ: IEEE, 2013. 91-92
Optical spectroscopy is a consolidated line of research with several translational opportunities in the industrial and clinical contexts. The reflected and transmitted light spectrum of gaseous, liquid and solid materials offers direct information about the identification and quantification of their components, its morphology, etc. Different fiber-optics and non-fiber optics systems acquire the spectrum depending on the application field. Supervised or blind analyses of the material's spectrum allow the separation of raw material, to know the presence and concentration of dangerous gases, the assessment on the correct recipes of textile dyes or the identification of tumors and cardiovascular pathologies.
Dean-Ben, X.L. ; Bühler, A. ; Ntziachristos, V. ; Razansky, D.
In: Oraevksy, A.A.* ; Wang, L.V.* [Eds.]: SPIE Photons Plus Ultrasound: Imaging and Sensing 2013 (Conference Photons Plus Ultrasound: Imaging and Sensing, San Francisco USA, 3-5 February 2013). Washington, USA: Society of Photo-Optical Instrumentation Engineers, 2013.:85810L (Proc. SPIE ; 8581)
Optoacoustic imaging offers the unique capability of simultaneous excitation of a three-dimensional (volumetric) region with a single interrogating laser pulse. In this way, three-dimensional imaging with single-shot illumination is theoretically achievable, which in principle allows the visualization of dynamic events at a high frame rate mainly limited by the pulse repetition rate of the laser. Simultaneous acquisition of optoacoustic signals at a set of points surrounding the imaging sample is however required for this purpose, which is hampered by several technical limitations related to lack of appropriate ultrasound detection technology, digital sampling and processing capacities. Also, a convenient reconstruction algorithm must be selected to accurately image the distribution of the optical absorption from the acquired signals. Specifically, the resolution and quantitativeness of the images depend on the reconstruction procedure employed. Herein we describe an accurate three-dimensional model-based optoacoustic reconstruction algorithm based on a convenient discretization of the analytical solution of the forward model. Subsequent algebraic inversion is done with the LSQR algorithm. The performance of the algorithm is showcased by reconstructing an excised mouse heart with a custom made three-dimensional optoacoustic imaging system. In this system, 256 optoacoustic signals corresponding to single-shot excitation are simultaneously collected with an array of ultrasonic transducers disposed on a spherical surface, which allows three-dimensional imaging at a frame rate of 10 Hz.
Dean-Ben, X.L. ; Ntziachristos, V. ; Razansky, D.
In: Oraevksy, A.A.* ; Wang, L.V.* [Eds.]: SPIE Photons Plus Ultrasound: Imaging and Sensing 2013 (Conference Photons Plus Ultrasound: Imaging and Sensing, San Francisco USA, 3-5 February 2013). Washington, USA: Society of Photo-Optical Instrumentation Engineers, 2013.:85813U (Proc. SPIE ; 8581)
The majority of optoacoustic reconstruction algorithms are based on the assumption that the speed of sound within the imaging sample is constant and equal to the speed of sound in the coupling medium, typically water. However, small speed of sound changes between different organs and structures are common in actual samples. The variations in the speed of sound within biological tissues are usually below 10% with respect to the speed of sound in water. Under these circumstances, the acoustic wave propagation can be modeled as acoustic rays and the main effect of the acoustic heterogeneities is the time-shifting of the optoacoustic signals. Herein, we describe a model-based reconstruction algorithm capable of accounting for such small speed of sound variations. It is based on modifying the integration curve in the forward optoacoustic model according to the time-shifting produced by differences in the speed of sound. The forward model is then discretized and inverted algebraically by means of the LSQR algorithm. The algorithm was tested experimentally with tissue-mimicking agar phantoms containing glycerine to simulate a higher speed of sound than water. The improvement in the image quality as compared to the results obtained by assuming a uniform speed of sound is discussed in this work.
Dean-Ben, X.L. ; Ntziachristos, V. ; Razansky, D.
In: Oraevksy, A.A.* ; Wang, L.V.* [Eds.]: SPIE Photons Plus Ultrasound: Imaging and Sensing 2013 (Conference Photons Plus Ultrasound: Imaging and Sensing, San Francisco USA, 3-5 February 2013). Washington, USA: Society of Photo-Optical Instrumentation Engineers, 2013.:85811P (Proc. SPIE ; 8581)
The high optoacoustic resolution at depths beyond the diffusive limit of light stems from the low scattering of sound, as compared to photons, within biological tissues. However, some biological samples contain strongly mismatched tissues such as bones or lungs that generally produce acoustic reflections and scattering, and image distortion is consequently produced by assuming an acoustically homogeneous medium. We describe herein a statistical procedure to modify the reconstruction algorithms in order to avoid such distortion. The procedure is based on weighting the contribution of the collected optoacoustic signals to the reconstruction with the probability that they are not affected by reflections or scattering. A rough estimation of such probability by considering an area enclosing the sample allows significantly reducing the artefacts associated to acoustic distortion. Furthermore, the available structural information of the imaging sample can be incorporated in the estimation of the distortion probability, in a way that a further improvement in the quality of the reconstructed images is achieved. The benefit of the reconstruction procedure described herein is showcased by reconstructing tissue mimicking phantoms containing air-gaps. In all cases, the image artefacts produced when no weighting is done are significantly reduced.
Dean-Ben, X.L. ; Bühler, A. ; Ntziachristos, V. ; Razansky, D.
In: Optical Molecular Probes, Imaging and Drug Delivery - Imaging in Tissue (Optical Molecular Probes, Imaging and Drug Delivery, 14 - 18 April 2013, Waikoloa Beach, Hawaii). Washington: OSA, 2013.:MTh2C.3
In this work we demonstrate a multispectral optoacoustic tomography system capable of real-time three-dimensional optoacoustic imaging of intrinsic anatomical and functional contrast as well as extrinsically-administered bio-markers in deep tissues.
Demski, H. ; Kalra, D.*
In: Proceedings of the EFMI STC (EFMI STC, Prague, 17-19 April 2013). European Federation for Medical Informatics, 2013.
Garcia-Allende, P. ; Nagengast, W.B.* ; Glatz, J. ; Ntziachristos, V.
In: Mahadevan-Jansen, A.* ; Vo-Dinh, T.* ; Grundfest, W.S.* [Eds.]: Advanced Biomedical and Clinical Diagnostic Systems XI (Advanced biomedical and clinical diagnostic systems, San Francisco USA, 3-5 February 2013). San Francisco, USA: Society of Photo-Optical Instrumentation Engineers, 2013.:85720Q (Proc. SPIE ; 8572)
Colorectal cancer (CRC) is the third most common form of cancer and, despite recent declines in both incidence and mortality, it still remains the second leading cause of cancer-related deaths in the western world. Colonoscopy is the standard for detection and removal of premalignant lesions to prevent CRC. The major challenges that physicians face during surveillance colonoscopy are the high adenoma miss-rates and the lack of functional information to facilitate decision-making concerning which lesions to remove. Targeted imaging with NIR fluorescence would address these limitations. Tissue penetration is increased in the NIR range while the combination with targeted NIR fluorescent agents provides molecularly specific detection of cancer cells, i.e. a red-flag detection strategy that allows tumor imaging with optimal sensitivity and specificity. The development of a flexible endoscopic fluorescence imaging method that can be integrated with standard medical endoscopes and facilitates the clinical use of this potential is described in this work. A semi-disposable coherent fiber optic imaging bundle that is traditionally employed in the exploration of biliary and pancreatic ducts is proposed, since it is long and thin enough to be guided through the working channel of a traditional video colonoscope allowing visualization of proximal lesions in the colon. A custom developed zoom system magnifies the image of the proximal end of the imaging bundle to fill the dimensions of two cameras operating in parallel providing the simultaneous color and fluorescence video acquisition.
Garcia-Allende, P. ; Glatz, J. ; Tjalma, J.J.* ; Terwissch, A. ; Scheltinga, V.* ; Koorstra, J.J.* ; Kleibeuker, J.H.* ; Dam, G.V.* ; Nagengast, W.B.* ; Ntziachristos, V.
In: Optical Molecular Probes, Imaging and Drug Delivery - New Probes For Functional Imaging (Optical Molecular Probes, Imaging and Drug Delivery, 14 - 18 April 2013, Waikoloa Beach, Hawaii United States). Washington: OSA, 2013. DOI 10.1364/OMP.2013.MW5C.6
Fluorescence molecular endoscopy is expected to have outstanding relevance regarding early cancer detection. Two alternative flexible endoscopic fluorescence imaging methods that facilitate clinical use of this potential are proposed and characterized in an animal study.
Glatz, J.* ; Garcia-Allende, P. ; Becker, V.* ; Koch, M. ; Meining, A.* ; Ntziachristos, V.
In: Optical Molecular Probes, Imaging and Drug Delivery OMP (Optical Molecular Probes, Imaging and Drug Delivery, Waikoloa Beach USA, 14-18 April 2013). Washington, USA: Optical Soc. America, 2013.
Fluorescence imaging plays an increasingly important role for the interventional identification and demarcation of tumor by visualizing molecular biomarkers. We showcase the usage of indocyanine green (ICG) for enhancing endoscopy of the pancreaticobiliary ducts in patients.
Kopanitsa, G. ; Hildebrand, C. ; Demski, H.
In: Lehmann, C.U.* ; Ammenwerth, E.* ; Nøhr, C.* [Eds.]: MEDINFO 2013. Proceedings of the 14th World Congress on Medical and Health Informatics (MEDINFO 2013, 20.08.2013, Kopenhagen, Dänemark). Amsterdam: IOS Press, 2013. 1097 (Stud. Health Technol. Inform. ; 192)
Maneas, E.* ; Tzoumas, S. ; Ntziachristos, V. ; Spyrou, G.*
In: Bioinformatics and Bioengineering (BIBE) (2013 IEEE 13th International Conference on Bioinformatics and Bioengineering (BIBE), 10-13 November 2013, Chania). Piscataway, NJ: IEEE, 2013. DOI: 10.1109/BIBE.2013.6701553
The aim of this study was the development of a simulator for Multispectral Optoacoustic Tomography (MSOT). The modelling pathway of the simulator was separated into the optical, the acoustic and the reconstruction part in generating finally a photoacoustic image. In this paper, the presented simulation geometry was based on a recently developed MSOT imaging system, but it can be easily modified to other imaging geometries. Through comparison between experimental and simulated data, a validation of the model as well as its limitations, perspectives and modifications are presented.
Sela, G.* ; Razansky, D. ; Shoham, S.*
In: Oraevksy, A.A.* ; Wang, L.V.* [Eds.]: Progress in biomedical optics and imaging ; 14 (SPIE Photons Plus Ultrasound: Imaging and Sensing 2013, San Francisco USA, 3-5 February 2013). Washington, USA: Society of Photo-Optical Instrumentation Engineers, 2013.:85812H (Proc. SPIE ; 8581)
Multiphoton microscopy is a powerful imaging modality that enables structural and functional imaging with cellular and sub-cellular resolution, deep within biological tissues. Yet, its main contrast mechanism relies on extrinsically administered fluorescent indicators. Here we developed a system for simultaneous multimodal optoacoustic and multiphoton fluorescence 3D imaging, which attains both absorption and fluorescence-based contrast by integrating an ultrasonic transducer into a two-photon laser scanning microscope. The system is readily shown to enable acquisition of multimodal microscopic images of fluorescently labeled targets and cell cultures as well as intrinsic absorption-based images of pigmented biological tissue. During initial experiments, it was further observed that that detected optoacoustically-induced response contains low frequency signal variations, presumably due to cavitation-mediated signal generation by the high repetition rate (80MHz) near IR femtosecond laser. The multimodal system may provide complementary structural and functional information to the fluorescently labeled tissue, by superimposing optoacoustic images of intrinsic tissue chromophores, such as melanin deposits, pigmentation, and hemoglobin or other extrinsic particle or dye-based markers highly absorptive in the NIR spectrum.
Voss, A.* ; Schroeder, R.* ; Fischer, C.* ; Heitmann, A.* ; Peters, A. ; Perz, S.
In: Conf. Proc. IEEE Eng. Med. Biol. Soc. (35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2013, 3 - 7 July 2013, Osaka, Japan). Piscataway, NJ: IEEE, 2013. 5574-5577:6610813 ( ; 2013)
Short-term heart rate variability (HRV) analyses (less than 30min) are suitable for ambulatory care and patient monitoring and can provide an almost immediate test result. Short-term 5 min HRV indices from nonlinear dynamics were determined from 782 females and 1124 males from the KORA S4 database. We applied various fractal and complexity measures with focus on entropies and investigated the influence of age in terms of five age decades (25-34, 35-44, 45-54, 55-64 and 65-74 years) and gender on these HRV indices. The analyses revealed significant modifications of the indices especially by age but partly also by gender especially in the younger groups. These results should be considered in future studies applying nonlinear dynamics, especially if major age and gender differences between the investigated groups are expected.

2012

Härdtner, C.* ; Multhoff, G. ; Falk, W.* ; Radons, J.*
Eur. J. Pharmacol. 684, 36-43 (2012)
Despite their toxic side effects prostaglandin H(2) synthase-2 (PGHS-2) inhibitors hold promise for cancer chemoprevention. In order to overcome adverse effects lower doses of PGHS-2 inhibitors could be applied in combination with other agents exhibiting complementary effects. Herein, the effects of the PGHS-2-specific inhibitor celecoxib either alone or in combination with the green tea-derived catechin (-)-epigallocatechin-3-gallate (EGCG) were studied on the expression of interleukin (IL)-1-induced tumorigenic factors in Colo357 human pancreatic adenocarcinoma cells. This approach mimics tumor-associated pancreatic inflammation which is considered as a key player in pancreatic malignancy. We found that co-incubation of Colo357 with celecoxib and EGCG synergistically diminished metabolic activity via apoptosis induction and down-regulated release of pro-angiogenic vascular endothelial growth factor (VEGF) and invasiveness-promoting matrix metalloproteinase (MMP)-2 to a maximum of 30%. Celecoxib and EGCG synergistically reduced IL-1-induced production of pro-inflammatory IL-6 and pro-angiogenic IL-8 to 23-50%. Celecoxib dose-dependently increased PGHS-2 levels. Whereas EGCG was able to compensate for celecoxib-mediated increase of PGHS-2, it failed to potentiate celecoxib-mediated suppression of prostaglandin E(2) (PGE(2)) release. Thus, in Colo357, EGCG synergistically boosts celecoxib-mediated effects and reduces the levels of celecoxib required to elicit beneficial effects on tumorigenic mediators by a factor of ten.
Wissenschaftlicher Artikel
Scientific Article
Kellnberger, S. ; Deliolanis, N.C. ; Queirós, D. ; Sergiadis, G.* ; Ntziachristos, V.
Opt. Lett. 37, 3423-3425 (2012)
Optoacoustic imaging has been primarily implemented in the time domain, i.e., using ultrashort nanosecond laser pulses for illumination. Alternatively, frequency domain optoacoustic imaging can be performed when employing amplitude modulated light sources. We present herein a tomographic implementation of optoacoustic imaging using a linear frequency modulated laser source. The method developed demonstrated the ability to produce tomographic images of optical absorbing phantoms and in vivo images, by enabling visualization of the mouse tail following ICG injection.
Wissenschaftlicher Artikel
Scientific Article
Böttger, E.* ; Multhoff, G. ; Kun, J.F.* ; Esen, M.*
PLoS ONE 7:e33774 (2012)
In the early immune response to Plasmodium falciparum-infected erythrocytes (iRBC), Natural Killer (NK) cells are activated, which suggests an important role in innate anti-parasitic immunity. However, it is not well understood whether NK cells directly recognize iRBC or whether stimulation of NK cells depends mainly on activating signals from accessory cells through cell-to-cell contact or soluble factors. In the present study, we investigated the influence of membrane-bound host Heat shock protein (Hsp) 70 in triggering cytotoxicity of NK cells from malaria-naïve donors or the cell line NK92 against iRBC. Hsp70 and HLA-E membrane expression on iRBC and potential activatory NK cell receptors (NKG2C, CD94) were assessed by flow cytometry and immunoblot. Upon contact with iRBC, Granzyme B (GzmB) production and release was initiated by unstimulated and Hsp70-peptide (TKD) pre-stimulated NK cells, as determined by Western blot, RT-PCR and ELISPOT analysis. Eryptosis of iRBC was determined by Annexin V-staining. Our results suggest that presence of Hsp70 and absence of HLA-E on the membrane of iRBC prompt the infected host cells to become targets for NK cell-mediated cytotoxicity, as evidenced by impaired parasite development. Contact of iRBC with NK cells induced release of GzmB. We propose that following GzmB uptake, iRBC undergo eryptosis via a perforin-independent, GzmB-mediated mechanism. Since NK activity toward iRBC could be specifically enhanced by TKD peptide and abrogated to baseline levels by blocking Hsp70 exposure, we propose TKD as an innovative immunostimulatory agent to be tested as an adjunct to anti-parasitic treatments in vivo.
Wissenschaftlicher Artikel
Scientific Article
Kääb, S.* ; Crawford, D.C.* ; Sinner, M.F.* ; Behr, E.R.* ; Kannankeril, P.J.* ; Wilde, A.A.* ; Bezzina, C.R.* ; Schulze-Bahr, E.* ; Guicheney, P.* ; Bishopric, N.H.* ; Myerburg, R.J.* ; Schott, J.J.* ; Pfeufer, A.* ; Beckmann, B.M.* ; Martens, E.* ; Zhang, T.* ; Stallmeyer, B.* ; Zumhagen, S.* ; Denjoy, I.* ; Bardai, A.* ; van Gelder, I.C.* ; Jamshidi, Y.* ; Dalageorgou, C.* ; Marshall, V.* ; Jeffery, S.* ; Shakir, S.* ; Camm, A.J.* ; Steinbeck, G.* ; Perz, S.* ; Lichtner, P. ; Meitinger, T. ; Peters, A. ; Wichmann, H.-E. ; Ingram, C.* ; Bradford, Y.* ; Carter, S.* ; Norris, K.* ; Ritchie, M.D.* ; George, A.L. Jr.* ; Roden, D.M.*
Circ. Cardiovasc. Genet. 5, 91-99 (2012)
BACKGROUND: Drug-induced long-QT syndrome (diLQTS) is an adverse drug effect that has an important impact on drug use, development, and regulation. We tested the hypothesis that common variants in key genes controlling cardiac electric properties modify the risk of diLQTS. METHODS AND RESULTS: In a case-control setting, we included 176 patients of European descent from North America and Europe with diLQTS, defined as documented torsades de pointes during treatment with a QT-prolonging drug. Control samples were obtained from 207 patients of European ancestry who displayed <50 ms QT lengthening during initiation of therapy with a QT-prolonging drug and 837 control subjects from the population-based KORA study. Subjects were successfully genotyped at 1424 single-nucleotide polymorphisms (SNPs) in 18 candidate genes including 1386 SNPs tagging common haplotype blocks and 38 nonsynonymous ion channel gene SNPs. For validation, we used a set of cases (n=57) and population-based control subjects of European descent. The SNP KCNE1 D85N (rs1805128), known to modulate an important potassium current in the heart, predicted diLQTS with an odds ratio of 9.0 (95% confidence interval, 3.5-22.9). The variant allele was present in 8.6% of cases, 2.9% of drug-exposed control subjects, and 1.8% of population control subjects. In the validation cohort, the variant allele was present in 3.5% of cases and in 1.4% of control subjects. CONCLUSIONS: This high-density candidate SNP approach identified a key potassium channel susceptibility allele that may be associated with the rare adverse drug reaction torsades de pointes.
Wissenschaftlicher Artikel
Scientific Article
Sinner, M.F.* ; Porthan, K.* ; Noseworthy, P.A.* ; Havulinna, A.S.* ; Tikkanen, J.T.* ; Müller-Nurasyid, M. ; Peloso, G.* ; Ulivi, S.* ; Beckmann, B.M.* ; Brockhaus, A.C. ; Cooper, R.R.* ; Gasparini, P.* ; Hengstenberg, C.* ; Hwang, S.-J.* ; Iorio, A.* ; Junttila, M.J.* ; Klopp, N. ; Kähönen, M.* ; Laaksonen, M.A.* ; Lehtimäki, T.* ; Lichtner, P. ; Lyytikäinen, L.-P.* ; Martens, E.* ; Meisinger, C. ; Meitinger, T. ; Merchant, F.M.* ; Nieminen, M.S.* ; Peters, A. ; Pietila, A.* ; Perz, S. ; Oikarinen, L.* ; Raitakari, O.* ; Reinhard, W.* ; Silander, K.* ; Thorand, B. ; Wichmann, H.-E. ; Sinagra, G.* ; Viikari, J.* ; O'Donnell, C.J.* ; Ellinor, P.T.* ; Huikuri, H.V.* ; Kääb, S.* ; Newton-Cheh, C.* ; Salomaa, V.*
Heart Rhythm 9, 1627-1634 (2012)
BACKGROUND The early repolarization pattern (ERP) is common and associated with risk of sudden cardiac death. ERP is heritable, and mutations have been described in syndromatic cases. OBJECTIVE To conduct a meta-analysis of genome-wide association studies to identify common genetic variants influencing ERP. METHODS We ascertained ERP on the basis of electrocardiograms in 3 large community-based cohorts from Europe and the United States: the Framingham Heart Study, the Health 2000 Study, and the KORA F4 Study. We analyzed genome-wide association studies in participants with and without ERP by logistic regression assuming an additive genetic model and meta-analyzed individual cohort results. We then sought to strengthen support for findings that reached P <= 1 x 10(-5) in independent individuals by direct genotyping or in-silico analysis of genome-wide data. We meta-analyzed the results from both stages. RESULTS Of 7482 individuals in the discovery stage, 452 showed ERP (ERP positive: mean age 46.9 +/- 8.9 years, 30.3% women; ERP negative: 47.5 +/- 9.4 years, 54.2% women). After meta-analysis, 8 single nucleotide polymorphisms reached P <= 1 x 10(-5): The most significant finding was intergenic rs11653989 (odds ratio 0.47; 95% confidence interval 0.36-0.61; P = 6.9 x 10(-9)). The most biologically relevant finding was intronic to KCND3: rs17029069 (odds ratio 1.46; 95% confidence interval 1.25-1.69; P = 8.5 x 10(-7)). In the replication step (7151 individuals), none of the 8 variants replicated, and combined meta-analysis results failed to reach genome-wide significance. CONCLUSIONS In a genome-wide association study, we were not able to reliably identify genetic variants predisposing to ERP, presumably due to insufficient statistical power and phenotype heterogeneity. The reported heritability of ERP warrants continued investigation in larger well-phenotyped populations.
Wissenschaftlicher Artikel
Scientific Article
Mohajer, M.* ; Engels, N. A.*
In: Proceedings (18th Annual Medicine Meets Virtual Reality (MMVR) Conference, 9-12 February 2011, Newport Beach, California). 2012.
Dean-Ben, X.L. ; Ntziachristos, V. ; Razansky, D.
IEEE Trans. Med. Imaging 31, 1154-1162 (2012)
Optoacoustic tomography has recently demonstrated powerful performance in small animal imaging and initial clinical trials in terms of the high spatial resolution, versatile contrast, and dynamic imaging capabilities it can provide. Yet, the current optoacoustic image reconstruction methods are usually based on inaccurate forward modelling approaches or otherwise demand a high computational cost, which imposes certain practical limitations and hinders image quantification. Herein, we introduce a new method for accelerating optoacoustic reconstructions, based on angular image discretization of the forward model solution. The method is particularly suitable for accurate image reconstruction with arbitrary meshes and space-dependent resolution, while it can also readily account for small speed of sound variations without compromising the calculation speed. It is further anticipated that the new approach will greatly facilitate development of high performance 3-D optoacoustic reconstruction methods.
Wissenschaftlicher Artikel
Scientific Article
Dean-Ben, X.L. ; Bühler, A. ; Ntziachristos, V. ; Razansky, D.
IEEE Trans. Med. Imaging 31, 1922-1928 (2012)
In many practical optoacoustic imaging implementations, dimensionality of the tomographic problem is commonly reduced into two dimensions or 1-D scanning geometries in order to simplify technical implementation, improve imaging speed or increase signal-to-noise ratio. However, this usually comes at a cost of significantly reduced quality of the tomographic data, out-of-plane image artifacts, and overall loss of image contrast and spatial resolution. Quantitative optoacoustic image reconstruction implies therefore collection of point 3-D (volumetric) data from as many locations around the object as possible. Here, we propose and validate an accurate model-based inversion algorithm for 3-D optoacoustic image reconstruction. Superior performance versus commonly-used backprojection inversion algorithms is showcased by numerical simulations and phantom experiments.
Wissenschaftlicher Artikel
Scientific Article
Kopanitsa, G. ; Tsvetkova, Z.* ; Veseli, H.
Stud. Health Technol. Inform. 180, 358-362 (2012)
Electronic health records are replacing conventional paper-based health records. For a doctor it is a working instrument, which can significantly reduce the time spent on paper work. Patients can benefit from accessing the electronic health records even though they usually do not have a medical background. Therefore, when specifying a graphical user interface (GUI) it is necessary to take into account the requirements of the different users: e.g. the functionality for the doctors and the presentation of data in an understandable manner for the patients. The study aims to review and analyze metrics used to evaluate the usability of user interfaces in health information systems. The scope of the search included the analysis of existing usability evaluating metrics that are applied both in healthcare and other domains, where the standard of storage and presentation of information are applied. We identified a set of metrics and evaluation methods that provide holistic evaluation facilities for graphical user interfaces.
Wissenschaftlicher Artikel
Scientific Article
Kopanitsa, G. ; Tsvetkova, Z.* ; Veseli, H.
In: Blobel, B.* ; Engelbrecht, R.* ; Shifrin, M.A.* [Eds.]: Large Scale Projects in eHealth - Partnership in Modernization (EFMI Special Topic Conference, 18–20 April 2012, Moscow, Russia). Amsterdam: IOS Press, 2012. 129-133 (Stud. Health Technol. Inform. ; 174)
Electronic health records are gradually replacing conventional paperbased health records. For a doctor, it is a working instrument, which can significantly reduce the time spent on paper work. At the same time, patients can benefit from accessing the electronic health records even though they usually do not have a medical background. Therefore, when specifying a graphical user interface (GUI) it is necessary to take into account the requirements of the different users: e.g. the functionality for the doctors and the presentation of data in an understandable manner for the patients. The study aims to review and analyze metrics used to evaluate the usability of user interfaces in health information systems. A literature review was performed to identify existing metrics. The scope of the search included the analysis of existing usability evaluation metrics that are applied both in healthcare and other domains, where standards for storage and presentation of information are applied. The analysis focused on metrics that are applicable for evaluating GUIs of health information systems. Several approaches and standards have been studied. Finally, a set of metrics and evaluation methods that provide holistic evaluation facilities for graphical user interfaces has been identified.
Kopanitsa, G. ; Tsvetkova, Z.* ; Veseli, H.
Stud. Health Technol. Inform. 180, IOS Press, 358-362 (2012)
Electronic health records are replacing conventional paper-based health records. For a doctor it is a working instrument, which can significantly reduce the time spent on paper work. Patients can benefit from accessing the electronic health records even though they usually do not have a medical background. Therefore, when specifying a graphical user interface (GUI) it is necessary to take into account the requirements of the different users: e.g. the functionality for the doctors and the presentation of data in an understandable manner for the patients. The study aims to review and analyze metrics used to evaluate the usability of user interfaces in health information systems. The scope of the search included the analysis of existing usability evaluating metrics that are applied both in healthcare and other domains, where the standard of storage and presentation of information are applied. We identified a set of metrics and evaluation methods that provide holistic evaluation facilities for graphical user interfaces.
Wissenschaftlicher Artikel
Scientific Article
Dean-Ben, X.L. ; Ntziachristos, V. ; Razansky, D.
J. Biomed. Opt. 17:110504 (2012)
ABSTRACT. The quality of optoacoustic tomographic reconstructions can be severely affected by acoustic reflections or scattering arising at interfaces of highly mismatched organs, such as bones, lungs, or other air-containing cavities. We present a procedure to reduce the associated artefacts based on estimation of the acoustic scatterers distribution within the imaged object. Signals generated by a strong optical absorber are processed and used in a weighted back-projection algorithm. Experimental results in a tissue-mimicking phantom clearly demonstrate improved performance as compared to the case in which no information on the distribution of acoustic scatterers is available.
Wissenschaftlicher Artikel
Scientific Article
Schilling, D. ; Bayer, C.* ; Emmerich, K.* ; Molls, M.* ; Vaupel, P.* ; Huber, R.M.* ; Multhoff, G.
Strahlenther. Onkol. 188, 353-358 (2012)
BACKGROUND AND PURPOSE: High levels of hypoxia inducible factor (HIF)-1α in tumors are reported to be associated with tumor progression and resistance to therapy. To examine the impact of HIF-1α on radioresistance under normoxia, the sensitivity towards irradiation was measured in human tumor cell lines that differ significantly in their basal HIF-1α levels. MATERIAL AND METHODS:HIF-1α levels were quantified in lysates of H1339, EPLC-272H, A549, SAS, XF354, FaDu, BHY, and CX- tumor cell lines by ELISA. Protein levels of HIF-1α, HIF-2α, carbonic anhydrase IX (CA IX), and GAPDH were assessed by Western blot analysis. Knock-down experiments were performed using HIF-1α siRNA. Clonogenic survival after irradiation was determined by the colony forming assay. RESULTS: According to their basal HIF-1α status, the tumor cell lines were divided into low (SAS, XF354, FaDu, A549, CX-), intermediate (EPLC-272H, BHY), and high (H1339) HIF-1α expressors. The functionality of the high basal HIF-1α expression in H1339 cells was proven by reduced CA IX expression after knocking-down HIF-1α. Linear regression analysis revealed no correlation between basal HIF-1α levels and the survival fraction at either 2 or 4 Gy in all tumor cell lines investigated. CONCLUSION: Our data suggest that basal HIF-1α levels in human tumor cell lines do not predict their radiosensitivity under normoxia.
Wissenschaftlicher Artikel
Scientific Article
Kopanitsa, G. ; Demski, H. ; Hildebrand, C.
In: Schreier, G.* ; Hayn, D.* ; Hörbst, A.* ; Ammenwerth, E.* [Eds.]: Proceedings (eHealth2012, 2012 Mai 10-11; Vienna, Austria). Wien: AIT Austrian Institute of Technology, 2012. 77-82 ( ; Proceedings of the eHealth2012)
Für eine effiziente Interaktion zwischen Arzt und elektronischer Krankenakte ist das Verständnis und somit die Darstellung der Inhalte entscheidend. Da die Benutzer unterschiedliche Hintergründe und verschiedene Blickwinkel bezüglich der Daten haben, sollten die Visualisierungsmethoden so flexibel sein, dass sich diese für jeden Benutzer optimal graphisch darstellen lassen. Das Anliegen unserer Forschung ist es, die Anforderungen an eine generische Visualisierungsmethode basierend auf dem 13606 Datenmodell zu spezifizieren. XML bietet eine gute Möglichkeit, Visualisierungsdaten zu bearbeiten und zu speichern. Das Format gestattet eine klare Strukturierung und Validierung der Daten basierend auf den integrierten Standardfunktionen. Das vorgeschlagene „Visuelle Medizinische Konzept“ ermöglicht die Trennung von medizinischem Wissen und Visualisierungskonzepten. Im Mittelpunkt unserer aktuellen Forschung steht die Definition eines optimalen XML Schemas für das Visuelle Medizinische Konzept, das eine generische Datenpräsentation für verschiedene Clients zulassen würde
Eguizabal, A.* ; Laughney, A.M.* ; Garcia-Allende, P. ; Krishnaswamy, V.* ; Wells, W.A.* ; Paulsen, K.D.* ; Pogue, B.W.* ; Lopez-Higuera, J.M.* ; Conde, O.M.*
Proc. SPIE 8230:823014 (2012)
A blind separation technique based on Independent Component Analysis (ICA) is proposed for breast tumor delineation and pathologic diagnosis. Tissue morphology is determined by fitting local measures of tissue reflectance to a Mie theory approximation, parameterizing the scattering power, scattering amplitude and average scattering irradiance. ICA is applied on the scattering parameters by spatial analysis using the Fast ICA method to extract more determinant features for an accurate diagnostic. Neither training, nor comparisons with reference parameters are required. Tissue diagnosis is provided directly following ICA application to the scattering parameter images. Surgically resected breast tissues were imaged and identified by a pathologist. Three different tissue pathologies were identified in 29 samples and classified as not-malignant, malignant and adipose. Scatter plot analysis of both ICA results and optical parameters where obtained. ICA subtle ameliorates those cases where optical parameter's scatter plots were not linearly separable. Furthermore, observing the mixing matrix of the ICA, it can be decided when the optical parameters themselves are diagnostically powerful. Moreover, contrast maps provided by ICA correlate with the pathologic diagnosis. The time response of the diagnostic strategy is therefore enhanced comparing with complex classifiers, enabling near real-time assessment of pathology during breast-conserving surgery.
Wissenschaftlicher Artikel
Scientific Article
Multhoff, G. ; Molls, M.* ; Radons, J.*
Front. Immunol. 2:98 (2012)
Chronic inflammatory mediators exert pleiotropic effects in the development of cancer. On the one hand, inflammation favors carcinogenesis, malignant transformation, tumor growth, invasion, and metastatic spread; on the other hand inflammation can stimulate immune effector mechanisms that might limit tumor growth. The link between cancer and inflammation depends on intrinsic and extrinsic pathways. Both pathways result in the activation of transcription factors such as NF-κB, STAT-3, and HIF-1 and in accumulation of tumorigenic factors in tumor and microenvironment. STAT-3 and NF-κB interact at multiple levels and thereby boost tumor-associated inflammation which can suppress anti-tumor immune responses. These factors also promote tumor growth, progression, and metastatic spread. IL-1, IL-6, TNF, and PGHS-2 are key mediators of an inflammatory milieu by modulating the expression of tumor-promoting factors. In this review we concentrate on the crucial role of pro-inflammatory mediators in inflammation-driven carcinogenesis and outline molecular mechanisms of IL-1 signaling in tumors. In addition, we elucidate the dual roles of stress proteins as danger signals in the development of anti-cancer immunity and anti-apoptotic functions.
Wissenschaftlicher Artikel
Scientific Article
Razansky, D. ; Deliolanis, N. ; Vinegoni, C.* ; Ntziachristos, V.
Curr. Pharm. Biotechnol. 13, 504-522 (2012)
For centuries, biological discoveries were based on optical imaging, in particular microscopy but also several chromophoric assays and photographic approaches. With the recent emergence of methods appropriate for bio-marker in vivo staining, such as bioluminescence, fluorescent molecular probes and proteins, as well as nanoparticle-based targeted agents, significant attention has been shifted toward in vivo interrogations of different dynamic biological processes at the molecular level. This progress has been largely supported by the development of advanced tomographic imaging technologies suitable for obtaining volumetric visualization of bio-marker distributions in small animals at a whole-body or whole-organ scale, an imaging frontier that is not accessible by the existing tissue-sectioning microscopic techniques due to intensive light scattering beyond the depth of a few hundred microns. Major examples of such recently developed optical imaging modalities are reviewed here, including bioluminescence tomography (BLT), fluorescence molecular tomography (FMT), and optical projection tomography (OPT). The pharmaceutical imaging community has quickly appropriated itself of these novel forms of optical imaging, since they come with very compelling advantages, such as quantitative three-dimensional capabilities, direct correlation to the biological cultures, easiness and cost-effectiveness of use, and the use of safe non-ionizing radiation. Some multi-modality approaches, combining light with other imaging modalities such as X-Ray CT or MRI, giving the ability to acquire both an optical contrast reconstruction along with a hi-fidelity anatomical images, are also reviewed. A separate section is devoted to the hybrid imaging techniques based on the optoacoustic phenomenon, such as multispectral optoacoustic tomography (MSOT), which are poised to leverage the traditional contrast and specificity advantages of optical spectrum by delivering an ever powerful set of capabilities, including real-time operation and high spatial resolution, not affected by the scattering nature of biological tissues.
Wissenschaftlicher Artikel
Scientific Article
Multhoff, G. ; Gaipl, U.S.* ; Niedermann, G.*
Strahlenther. Onkol. 188, 312-315 (2012)
Ziel einer effektiven Tumortherapie ist es, sowohl das Wachstum des Primärtumors zu kontrollieren, als auch langanhaltende und spezifische Antitumor-Immunantworten gegen den Primärtumor, Rezidive und Metastasen zu induzieren. An der Eliminierung von Tumor- sowie bakteriell und viral infizierten Zellen sind im Wesentlichen die antigenspezifischen CD8+ zytotoxischen und CD4+ T-Helferzellen, die beide dem adaptiven Immunsystem angehören, und die natürlichen Killerzellen (NK), die als Mitglieder der angeborenen Immunabwehr Zielzellen ohne vorherige antigenspezifische Stimulation lysieren, beteiligt.
Wissenschaftlicher Artikel
Scientific Article
Schmid, T.E.* ; Zlobinskaya, O.* ; Multhoff, G.
Curr. Genomics 13, 418-425 (2012)
The use of particle ion beams in cancer radiotherapy has a long history. Today, beams of protons or heavy ions, predominantly carbon ions, can be accelerated to precisely calculated energies which can be accurately targeted to tumors. This particle therapy works by damaging the DNA of tissue cells, ultimately causing their death. Among the different types of DNA lesions, the formation of DNA double strand breaks is considered to be the most relevant of deleterious damages of ionizing radiation in cells. It is well-known that the extremely large localized energy deposition can lead to complex types of DNA double strand breaks. These effects can lead to cell death, mutations, genomic instability, or carcinogenesis. Complex double strand breaks can increase the probability of mis-rejoining by NHEJ. As a consequence differences in the repair kinetics following high and low LET irradiation qualities are attributed mainly to quantitative differences in their contributions of the fast and slow repair component. In general, there is a higher contribution of the slow component of DNA double strand repair after exposure to high LET radiation, which is thought to reflect the increased amount of complex DNA double strand breaks. These can be accurately measured by the γ-H2AX assay, because the number of phosphorylated H2AX foci correlates well with the number of double strand breaks induced by low or / and high LET radiation.
Wissenschaftlicher Artikel
Scientific Article
Scheuer, W.* ; van Dam, G.M.* ; Dobosz, M.* ; Schwaiger, M.* ; Ntziachristos, V.
Sci. Transl. Med. 4:134ps11 (2012)
Fluorescent agents with specificity to cellular and subcellular moieties present promise for enhancing diagnostics and theranostics, yet challenges associated with regulatory approvals of experimental agents stifle the clinical translation. As a result, targeted fluorescent agents have remained predominantly as preclinical imaging tools. We discuss the potential of using optically labeled drugs to accelerate the clinical acceptance of optical and optoacoustic agents, in analogy to nuclear medicine approaches. This strategy, corroborated with microdosing studies, outlines a promising approach for overcoming bottlenecks and advancing photonic clinical imaging.
Wissenschaftlicher Artikel
Scientific Article
Rosenthal, A. ; Jetzfellner, T. ; Razansky, D. ; Ntziachristos, V.
IEEE Trans. Med. Imaging 31, 1346-1357 (2012)
The use of model-based algorithms in tomographic imaging offers many advantages over analytical inversion methods. However, the relatively high computational complexity of model-based approaches often restricts their efficient implementation. In practice, many modern imaging modalities, such as computed-tomography, positron-emission tomography, or optoacoustic tomography, normally use a very large number of pixels/voxels for image reconstruction. Consequently, the size of the forward-model matrix hinders the use of many inversion algorithms. In this paper, we present a new framework for model-based tomographic reconstructions, which is based on a wavelet-packet representation of the imaged object and the acquired projection data. The frequency localization property of the wavelet-packet base leads to an approximately separable model matrix, for which reconstruction at each spatial frequency band is independent and requires only a fraction of the projection data. Thus, the large model matrix is effectively separated into a set of smaller matrices, facilitating the use of inversion schemes whose complexity is highly nonlinear with respect to matrix size. The performance of the new methodology is demonstrated for the case of 2-D optoacoustic tomography for both numerically generated and experimental data.
Wissenschaftlicher Artikel
Scientific Article
Eguizabal, A.* ; Laughney, A.M.* ; Garcia-Allende, P. ; Krishnaswamy, V.* ; Wells, W.A.* ; Paulsen, K.D.* ; Pogue, B.W.* ; Lopez-Higuera, J.M.* ; Conde, O.M.*
Proc. SPIE 8230:823010 (2012)
A spectral analysis technique to enhance tumor contrast during breast conserving surgery is proposed. A set of 29 surgically-excised breast tissues have been imaged in local reflectance geometry. Measures of broadband reflectance are directly analyzed using Principle Component Analysis (PCA), on a per sample basis, to extract areas of maximal spectral variation. A dynamic selection threshold has been applied to obtain the final number of principal components, accounting for inter-patient variability. A blind separation technique based on Independent Component Analysis (ICA) is then applied to extract diagnostically powerful results. ICA application reveals that the behavior of one independent component highly correlates with the pathologic diagnosis and it surpasses the contrast obtained using empirical models. Moreover, blind detection characteristics (no training, no comparisons with training reference data) and no need for parameterization makes the automated diagnosis simple and time efficient, favoring its translation to the clinical practice. Correlation coefficient with model-based results up to 0.91 has been achieved.
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Scientific Article
Wildgruber, M.* ; Settles, M.* ; Kosanke, K.* ; Bielicki, I.* ; Ntziachristos, V. ; Rummeny, E.J.* ; Botnar, R.M.* ; Huber, A.M.*
J. Magn. Reson. Imaging 36, 1372-1382 (2012)
PURPOSE: To evaluate phase-sensitive inversion-recovery (PSIR) imaging at 1.5 T in a mouse model of permanent coronary artery ligation as a potentially rapid and robust alternative for the accurate assessment of myocardial infarction (MI) by cardiac magnetic resonance imaging (MRI). MATERIALS AND METHODS: PSIR late gadolinium enhancement (LGE) imaging was compared to conventional 2D segmented inversion-recovery imaging for the assessment of murine MI. RESULTS: PSIR images provided comparable contrast and kinetics of intravenously injected gadopentetate dimeglumine (Gd-DTPA). At the mid-ventricular level there was good agreement between conventional IR and PSIR for infarct size assessment. After intravenous injection a limited time window of ∼6 minutes is available for delayed enhancement imaging in mice. Whole-heart infarct imaging with 1 mm thick slices was only possible in this restricted time frame when the PSIR method is applied, avoiding the need for repetitively adapting the correct inversion time. Infarct size determined by PSIR MRI demonstrated good agreement with postmortem histology. Infarct size determined by PSIR LGE MRI inversely correlates with left-ventricular function on day 7 after MI. CONCLUSION: The PSIR technique provides stable and consistent contrast between hyperenhanced and remote myocardium independent of the selected inversion time (TI) and proved to be a robust, fast, and accurate tool for the assessment of MI in mice.
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Scientific Article
Taruttis, A. ; Razansky, D. ; Ntziachristos, V.
In: Oraevsky, A.A.* ; Wang, L.V.* [Eds.]: Proceedings (SPIE Photons Plus Ultrasound: Imaging and Sensing 2012). Bellingham, USA: International Soc. for Optics and Photonics, 2012.:822302 (Proc. SPIE ; 8223)
Optoacoustic imaging has enabled the visualization of optical contrast at high resolutions in deep tissue. Our Multispectral optoacoustic tomography (MSOT) imaging results reveal internal tissue heterogeneity, where the underlying distribution of specific endogenous and exogenous sources of absorption can be resolved in detail. Technical advances in cardiac imaging allow motion-resolved multispectral measurements of the heart, opening the way for studies of cardiovascular disease. We further demonstrate the fast characterization of the pharmacokinetic profiles of lightabsorbing agents. Overall, our MSOT findings indicate new possibilities in high resolution imaging of functional and molecular parameters.
Taruttis, A. ; Morscher, S. ; Burton, N.C. ; Razansky, D. ; Ntziachristos, V.
PLoS ONE 7:e30491 (2012)
The characterization of pharmacokinetic and biodistribution profiles is an essential step in the development process of new candidate drugs or imaging agents. Simultaneously, the assessment of organ function related to the uptake and clearance of drugs is of great importance. To this end, we demonstrate an imaging platform capable of high-rate characterization of the dynamics of fluorescent agents in multiple organs using multispectral optoacoustic tomography (MSOT). A spatial resolution of approximately 150 µm through mouse cross-sections allowed us to image blood vessels, the kidneys, the liver and the gall bladder. In particular, MSOT was employed to characterize the removal of indocyanine green from the systemic circulation and its time-resolved uptake in the liver and gallbladder. Furthermore, it was possible to track the uptake of a carboxylate dye in separate regions of the kidneys. The results demonstrate the acquisition of agent concentration metrics at rates of 10 samples per second at a single wavelength and 17 s per multispectral sample with 10 signal averages at each of 5 wavelengths. Overall, such imaging performance introduces previously undocumented capabilities of fast, high resolution in vivo imaging of the fate of optical agents for drug discovery and basic biological research.
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Scientific Article
Ma, R. ; Söntges, S. ; Shoham, S. ; Ntziachristos, V. ; Razansky, D.
Biomed. Opt. Express 3, 1724-1731 (2012)
The hybrid nature of optoacoustic imaging might impose limitations on concurrent placement of optical and ultrasonic detection components, especially in high resolution microscopic applications that require dense arrangements and miniaturization of components. This hinders optimal deployment of the optical excitation and ultrasonic detection paths, leading to reduction of imaging speed and spatial resolution performance. We suggest a compact coaxial design for optoacoustic microscopy that allows optimizing both the light illumination and ultrasonic detection parameters of the imaging system. System performance is showcased in phantoms and in vivo imaging of microvasculature, achieving real time operation in two dimensions and penetration of 6 mm into optically dense human tissues.
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Ale, A.B.F ; Ermolayev, V. ; Herzog, E. ; Cohrs, C.M. ; Hrabě de Angelis, M. ; Ntziachristos, V.
Nat. Methods 9, 615-620 (2012)
The development of hybrid optical tomography methods to improve imaging performance has been suggested over a decade ago and has been experimentally demonstrated in animals and humans. Here we examined in vivo performance of a camera-based hybrid fluorescence molecular tomography (FMT) system for 360° imaging combined with X-ray computed tomography (XCT). Offering an accurately co-registered, information-rich hybrid data set, FMT-XCT has new imaging possibilities compared to stand-alone FMT and XCT. We applied FMT-XCT to a subcutaneous 4T1 tumor mouse model, an Aga2 osteogenesis imperfecta model and a Kras lung cancer mouse model, using XCT information during FMT inversion. We validated in vivo imaging results against post-mortem planar fluorescence images of cryoslices and histology data. Besides offering concurrent anatomical and functional information, FMT-XCT resulted in the most accurate FMT performance to date. These findings indicate that addition of FMT optics into the XCT gantry may be a potent upgrade for small-animal XCT systems.
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Abou-Elkacem, L.* ; Björn, S. ; Doleschel, D.* ; Ntziachristos, V. ; Schulz, R.B. ; Hoffman, R.M.* ; Kiessling, F.* ; Lederle, W.*
Eur. Radiol. 22, 1955-1962 (2012)
To compare mesoscopic epi-fluorescence tomography (MEFT) and EPRI-illumination reflectance imaging (EPRI) for quantitative tumour size assessment in mice. Tumour xenografts of green/red fluorescent protein (GFP/RFP)-expressing colon cancer cells were measured using MEFT, EPRI, ultrasound (US) and micro computed tomography (mu CT) at day 14 post-injection (n = 6). Results from MEFT and EPRI were correlated with each other and with US and mu CT (reference methods). Tumour volumes were measured ex vivo by GFP and RFP fluorescence imaging on cryoslices and compared with the in vivo measurements. High correlation and congruency were observed between MEFT, US and mu CT (MEFT/US: GFP: r (2) = 0.96; RFP: r (2) = 0.97, both P < 0.05; MEFT/mu CT: GFP: r (2) = 0.93; RFP: r (2) = 0.90; both P < 0.05). Additionally, in vivo MEFT data were highly correlated and congruent with ex vivo cryoslice imaging results (GFP: r (2) = 0.96; RFP: r (2) = 0.99; both P < 0.05). In comparison, EPRI significantly overestimated tumour volumes (P < 0.05), although there was a significant correlation with US and mu CT (EPRI/US: GFP: r (2) = 0.95; RFP: r (2) = 0.94; both P < 0.05; EPRI/mu CT GFP: r (2) = 0.86; RFP: r (2) = 0.86; both P < 0.05). Fluorescence distribution reconstruction using MEFT affords highly accurate three-dimensional (3D) tumour volume data showing superior accuracy compared to EPRI. Thus, MEFT is a very suitable technique for quantitatively assessing fluorescence distribution in superficial tumours at high spatial resolution. aEuro cent Mesoscopic epi-fluorescence tomography (MEFT) is an important new molecular imaging technique. aEuro cent MEFT allows accurate size determination of superficial tumours with high resolution. aEuro cent MEFT is a suitable technique for longitudinal assessment of tumour growth. aEuro cent MEFT allows 3D reconstruction and quantification of fluorescence distributions.
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Scientific Article
Bühler, A.* ; Morscher, S.* ; Razansky, D. ; Ntziachristos, V.
In: Oraevsky, A.A.* ; Wang, L.V.* [Eds.]: Proceedings (SPIE Photons Plus Ultrasound: Imaging and Sensing 2012,). Bellingham, USA: International Soc. for Optics and Photonics, 2012.:82230H (Proceedings of SPIE ; 8223)
The ability to detect molecular probes in deep tissue, based on optical signatures, has been limited by tissue scattering, which reduces the spatial resolution and complicates quantification. To address this challenge, multispectral optoacoustic tomography (MSOT) has been recently introduced, a hybrid technology that capitalizes on the optoacoustic effect to combine rich optical contrast with the high spatial resolution and real-time operation of ultrasound. Using multiwavelength illumination MSOT can visualize molecular probes based on their distinct optical absorption spectra through several millimeters to centimeters of tissue. Herein we present a whole body multi-spectral optoacoustic tomography system and report on spectral processing techniques for detection of molecular probes in living mice.
Bühler, A. ; Herzog, E. ; Ale, A.B.F ; Smith, B.D.* ; Ntziachristos, V. ; Razansky, D.
EJNMMI Res. 2, 1-6:14 (2012)
BACKGROUND: Tumor targeting is of high clinical and biological relevance, and major efforts have been made to develop molecular imaging technologies for visualization of the disease markers in tissue. Of particular interest is apoptosis which has a profound role within tumor development and has significant effect on cancer malignancy. METHODS: Herein, we report on targeting of phosphatidylserine-exposing cells within live tumor allograft models using a synthetic near infrared zinc(II)-dipicolylamine probe. Visualization of the probe biodistribution is performed with whole body multispectral optoacoustic tomography (MSOT) system and subsequently compared to results attained by planar and tomographic fluorescence imaging systems. RESULTS: Compared to whole body optical visualization methods, MSOT attains remarkably better imaging capacity by delivering high-resolution scans of both disease morphology and molecular function in real time. Enhanced resolution of MSOT clearly showed that the probe mainly localizes in the vessels surrounding the tumor, suggesting that its tumor selectivity is gained by targeting the phosphatidylserine exposed on the surface of tumor vessels. CONCLUSIONS: The current study demonstrates the high potential of MSOT to broadly impact the fields of tumor diagnostics and preclinical drug development.
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Scientific Article
Bühler, A. ; Morscher, S. ; Razansky, D. ; Ntziachristos, V.
In: In Vivo Preclinical Imaging (Photons Plus Ultrasound: Imaging and Sensing, San Francisco, 21 January 2012). SPIE, 2012.:82230H (Proc. SPIE ; 8223)
The ability to detect molecular probes in deep tissue, based on optical signatures, has been limited by tissue scattering, which reduces the spatial resolution and complicates quantification. To address this challenge, multispectral optoacoustic tomography (MSOT) has been recently introduced, a hybrid technology that capitalizes on the optoacoustic effect to combine rich optical contrast with the high spatial resolution and real-time operation of ultrasound. Using multiwavelength illumination MSOT can visualize molecular probes based on their distinct optical absorption spectra through several millimeters to centimeters of tissue. Herein we present a whole body multi-spectral optoacoustic tomography system and report on spectral processing techniques for detection of molecular probes in living mice.
Mohajer, M. ; Schmid, V.J.* ; Braren, R.* ; Noel, P.B.* ; Englmeier, K.-H.
In: Nuclear and Plasma Sciences Society* [Ed.]: IEEE Nuclear Science Symposium Conference Record (2011 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2011, Valencia, 23-29. Oktober 2011). Piscataway, NJ: IEEE, 2012. 2483-2487
We introduce a method for the heterogeneity analysis of liver tissue and other enhanced organs in the Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) of the liver based on the similarity of enhancement patterns of signal curves. This analysis is done by an iterative piecewise hierarchical clustering method. The novel idea of the clustering algorithm is a new similarity measure which compares the wash out part of the signal curves for parallelism. To enhance signal-to-noise ratio, the signal curves are derived from a reduced subspace with the help of principle component analysis. The method is evaluated on nine DCE-MRI liver datasets from patients with different kinds of tumors. The heterogeneity analysis is based on the fact that the distance between the signal curves of the voxels belonging to a homogeneous group to the mean curve of this group is smaller than the distance of the signal curves to the mean of a heterogeneous group with the same number of voxels. On the other hand, as the liver is a heterogeneous organ, there are voxels inside the tissue, which neighbors are part of several homogeneous areas. The experiments on nine liver datasets show that depending on the expected granularity, the tissue of liver can consist of many sub regions. This method is a suitable way to increase signal to noise ratio. The clustering gives us information about how many significant different signal curves are present in a dataset. This information helps the estimation of number of compartments and the complexity of the system.
Eguizabal, A.* ; Laughney, A.M.* ; Garcia-Allende, P. ; Krishnaswamy, V.* ; Wells, W.A.* ; Paulsen, K.D.* ; Pogue, B.W.* ; Lopez-Higuera, J.M.* ; Conde, O.M.*
In: Proceedings of the 9th IEEE International Symposium on Biomedical Imaging (From Nano to Macro ISBI 2012, Barcelona, 2-5 May 2012). Piscataway, NJ: IEEE, 2012. 1611-1614
A surgeon-guided independent component analysis from optical reflectance measurements is proposed for breast tumor delineation. Independent Component Analysis is first applied to extract the most relevant features from local measures of broadband reflectance and then a tumor probability indicator is obtained and provided utilizing surgeon assistance to resolve the inherent ambiguities in the independent component calculation. A set of 29 breast tissue samples have been diagnosed achieving a sensitivity of 90.57%, and specificity of 93.98%.
Gehrmann, M. ; Stangl, S. ; Kirschner, A. ; Foulds, G.A. ; Sievert, W. ; Doß, B.T. ; Walch, A.K. ; Pockley, A.G.* ; Multhoff, G.
PLoS ONE 7:e41341 (2012)
BACKGROUND: We have previously reported that human recombinant granzyme B (grB) mediates apoptosis in membrane heat shock protein 70 (Hsp70)-positive tumor cells in a perforin-independent manner. METHODOLOGY/PRINCIPAL FINDINGS: Optical imaging of uptake kinetics revealed co-localization of grB with recycling endosomes (Rab9/11) as early as 5 min after internalization, with late endosomes (Rab7) after 30 min, and the lysosomal compartment (LAMP1/2) after 60 to 120 min. Active caspase-3-mediated apoptosis was induced in mouse CT26 monolayer cells and 3D tumor spheroids, but not in normal mouse endothelial cells. Granzyme B selectively reduced the proportion of membrane Hsp70-positive cells in CT26 tumor spheroids. Consecutive i.v. injections of recombinant human grB into mice bearing membrane Hsp70-positive CT26 tumors resulted in significant tumor suppression, and a detailed inspection of normal mouse organs revealed that the administration of anti-tumoral concentrations of grB elicited no clinicopathological changes. CONCLUSIONS/SIGNIFICANCE: These findings support the future clinical evaluation of human grB as a potential adjuvant therapeutic agent, especially for treating immunosuppressed patients that bear membrane Hsp70-positive tumors.
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Scientific Article
Radrich, K. ; Ale, A.B.F ; Ermolayev, V. ; Ntziachristos, V.
J. Biomed. Opt. 17:126011 (2012)
We examine the improvement in imaging performance, such as axial resolution and signal localization, when employing limited-projection-angle fluorescence molecular tomography (FMT) together with x-ray computed tomography (XCT) measurements versus stand-alone FMT. For this purpose, we employed living mice, bearing a spontaneous lung tumor model, and imaged them with FMT and XCT under identical geometrical conditions using fluorescent probes for cancer targeting. The XCT data was employed, herein, as structural prior information to guide the FMT reconstruction. Gold standard images were provided by fluorescence images of mouse cryoslices, providing the ground truth in fluorescence bio-distribution. Upon comparison of FMT images versus images reconstructed using hybrid FMT and XCT data, we demonstrate marked improvements in image accuracy. This work relates to currently disseminated FMT systems, using limited projection scans, and can be employed to enhance their performance.
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Mallas, G.* ; Brooks, D.H.* ; Rosenthal, A. ; Nudelman, R.N. ; Mauskapf, A.* ; Jaffer, F.A.* ; Ntziachristos, V.
Phys. Med. Biol. 57, 6395-6406 (2012)
Intravascular near-infrared fluorescence (iNIRF) imaging can enable the in vivo visualization of biomarkers of vascular pathology, including high-risk plaques. The technique resolves the bio-distribution of systemically administered fluorescent probes with molecular specificity in the vessel wall. However, the geometrical variations that may occur in the distance between fibre-tip and vessel wall can lead to signal intensity variations and challenge quantification. Herein we examined whether the use of anatomical information of the cross-section vessel morphology, obtained from co-registered intravascular ultrasound (IVUS), can lead to quantification improvements when fibre-tip and vessel wall distance variations are present. The algorithm developed employs a photon propagation model derived from phantom experiments that is used to calculate the relative attenuation of fluorescence signals as they are collected over 360° along the vessel wall, and utilizes it to restore accurate fluorescence readings. The findings herein point to quantification improvements when employing hybrid iNIRF, with possible implications to the clinical detection of high-risk plaques or blood vessel theranostics.
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Schmieder, A.* ; Multhoff, G. ; Radons, J.*
Cytokine 60, 514-521 (2012)
Human pancreatic cancer is one of the most fatal of all solid tissue malignancies. Pancreatic inflammation plays a key role in the development of pancreatic malignancy mediated by pro-inflammatory signalling cascades. Despite advances in surgery and radiation oncology, no significant improvements in overall survival have yet been achieved. Recent investigations suggest a crucial role of interleukin-33 (IL-33), a novel IL-1 family cytokine, in the pathogenesis of chronic pancreatitis and possibly pancreatic cancer. However, the precise role of IL-33 in pancreatic carcinogenesis is poorly understood. As IL-33 mediates its effects via the heterodimeric ST2L/IL-1 receptor accessory protein (IL-1RAcP) receptor complex, we investigated the influence of IL-33 alone, IL-33 combined with IL-1 and other inflammatory cytokines on IL-33 receptor/ligand mRNA expression and production of tumorigenic factors in the highly metastatic human pancreatic adenocarcinoma cell line Colo357. Our results demonstrated that IL-1 and IL-3 up-regulated IL-33 mRNA while IL-12 showed the opposite effect. We also detected a counter-regulatory effect of IL-33 and IL-1 on the mRNA expression of soluble IL-33 receptor ST2 and membrane-bound receptor ST2L. Furthermore, IL-33 and IL-1 acted synergistically in up-regulating secretion of pro-inflammatory IL-6. IL-33 alone stimulated spontaneous release of pro-angiogenic IL-8, but it did not affect IL-1-induced IL-8 secretion. IL-33/IL-1 effects on cytokine production appear to be mediated via NF-κB activation. These data argue for the pro-inflammatory role of IL-33 in Colo357 cells implying that IL-33 might act as a crucial mediator in inflammation-associated pancreatic carcinogenesis.
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Veseli, H.
In: Proceedings (International Conference on Interoperability for Enterprise Systems and Applications I-ESA'12, March 22-23 2012, Valencia, Spain). Valencia: Universitat Politecnica de Valencia, 2012.
Semantic interoperability of EHR (electronic health records) is a major challenge in medical informatics. In the presented solution the electronic commuincation barriers caused by heterogeneous EHR systems are exemplified in a regional doctors’ network in Germany.  EHR interoperability is enabled by a canonical model of clinical data using EHR standards such as ISO 13606 and ASTM CCR. In addition a server is developed which handles the data exchange so systems have to communicate only to one party. The developed server provides state of the art comunication interfaces but offers solutions for those EHR systems which cannot fulfill modern interoperability requirements. This ensures high participation within the network. The server also offers rich vizualization capabilities (that are applied on the exchanged data), this adds value to the data exchange solution.
López Bolós, J. ; Hildebrand, C. ; Demski, H.
In: Proceedings (AAL Forum 2012, 24-27 September 2012, Eindhoven, Netherlands). Eindhoven: Smart Homes, 2012.
Loneliness and social isolation in the elderly are major problems in elderly care. In many European countries more than half of the people over the age of 75 live alone and 12% of older people feel trapped in their own homesResearch has shown that being alone in old age will often lead to social deprivation, low self-esteem or physical inability and also that there is a strong correlation between social isolation and poor health. Join-In aims at counteracting loneliness in the elderly by providing a methodology and technologies for elderly persons to participate in social activities and to make them part of society. By offering useful activities that encourage communication we aim to help the elderly to meet and exchange with others.  
Lozano, N.* ; Al-Jamal, W.T.* ; Taruttis, A. ; Bézière, N. ; Burton, N.C. ; Van den Bossche, J.* ; Mazza, M.* ; Herzog, E. ; Ntziachristos, V. ; Kostarelos, K.*
J. Am. Chem. Soc. 134, 13256-13258 (2012)
The design of liposome-nanoparticle hybrids offers a rich toolbox for the fabrication of multifunctional modalities. A self-assembled liposome-gold nanorod hybrid vesicular system that consists of lipid-bilayer-associated gold nanorods designed to allow deep tissue detection, therapy, and monitoring in living animals using multispectral optoacoustic tomography has been fabricated and characterized in vitro and in vivo.
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Schmid, T.E.* ; Greubel, C.* ; Hable, V.* ; Zlobinskaya, O.* ; Michalski, D.* ; Girst, S.* ; Siebenwirth, C.* ; Schmid, E.* ; Molls, M.* ; Multhoff, G. ; Dollinger, G.*
Phys. Med. Biol. 57, 5889-5907 (2012)
This study shows that enhanced radiobiological effectiveness (RBE) values can be generated focusing low linear energy transfer (LET) radiation and thus changing the microdose distribution. 20 MeV protons (LET = 2.65 keV µm(-1)) are focused to submicrometer diameter at the ion microprobe superconducting nanoprobe for applied nuclear (Kern) physics experiments of the Munich tandem accelerator. The RBE values, as determined by measuring micronuclei (RBE(MN) = 1.48 ± 0.07) and dicentrics (RBE(D) = 1.92 ± 0.15), in human-hamster hybrid (A(L)) cells are significantly higher when 117 protons were focused to a submicrometer irradiation field within a 5.4 × 5.4 µm(2) matrix compared to quasi homogeneous in a 1 × 1 µm(2) matrix applied protons (RBE(MN) = 1.28 ± 0.07; RBE(D) = 1.41 ± 0.14) at the same average dose of 1.7 Gy. The RBE values are normalized to standard 70 kV (dicentrics) or 200 kV (micronuclei) x-ray irradiation. The 117 protons applied per point deposit the same amount of energy like a (12)C ion with 55 MeV total energy (4.48 MeV u(-1)). The enhancements are about half of that obtained for (12)C ions (RBE(MN) = 2.20 ± 0.06 and RBE(D) = 3.21 ± 0.10) and they are attributed to intertrack interactions of the induced damages. The measured RBE values show differences from predictions of the local effect model (LEM III) that is used to calculate RBE values for irradiation plans to treat tumors with high LET particles.
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Vinegoni, C.* ; Fumene Feruglio, P.* ; Razansky, D. ; Gorbatov, R.* ; Ntziachristos, V. ; Sbarbati, A.* ; Nahrendorf, M.* ; Weissleder, R.*
PLoS ONE 7:e34427 (2012)
o date there is a lack of tools to map the spatio-temporal dynamics of diverse cells in experimental heart models. Conventional histology is labor intensive with limited coverage, whereas many imaging techniques do not have sufficiently high enough spatial resolution to map cell distributions. We have designed and built a high resolution, dual channel Born-normalized near-infrared fluorescence optical projection tomography system to quantitatively and spatially resolve molecular agents distribution within whole murine heart. We validated the use of the system in a mouse model of monocytes/macrophages recruitment during myocardial infarction. While acquired, data were processed and reconstructed in real time. Tomographic analysis and visualization of the key inflammatory components were obtained via a mathematical formalism based on left ventricular modeling. We observed extensive monocyte recruitment within and around the infarcted areas and discovered that monocytes were also extensively recruited into non-ischemic myocardium, beyond that of injured tissue, such as the septum.
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Ellinor, P.T.* ; Lunetta, K.L.* ; Albert, C.M.* ; Glazer, N.L.* ; Ritchie, M.D.* ; Smith, A.V.* ; Arking, D.E.* ; Müller-Nurasyid, M. ; Krijthe, B.P.* ; Lubitz, S.A.* ; Bis, J.C.* ; Chung, M.K.* ; Doerr, M.* ; Ozaki, K.* ; Roberts, J.D.* ; Smith, J.G.* ; Pfeufer, A. ; Sinner, M.F.* ; Lohman, K.* ; Ding, J.Z.* ; Smith, N.L.* ; Smith, J.D.* ; Rienstra, M.* ; Rice, K.M.* ; van Wagoner, D.R.* ; Magnani, J.W.* ; Wakili, R.* ; Clauss, S.* ; Rotter, J.I.* ; Steinbeck, G.* ; Launer, L.J.* ; Davies, R.W.* ; Borkovich, M.* ; Harris, T.B.* ; Lin, H.H.* ; Völker, U.* ; Völzke, H.* ; Milan, D.J.* ; Hofman, A.* ; Boerwinkle, E.* ; Chen, L.Y.* ; Soliman, E.Z.* ; Voight, B.F.* ; Li, G.* ; Chakravarti, A.* ; Kubo, M.* ; Tedrow, U.B.* ; Rose, L.M.* ; Ridker, P.M.* ; Conen, D.* ; Tsunoda, T.* ; Furukawa, T.* ; Sotoodehnia, N.* ; Xu, S.Y.* ; Kamatani, N.* ; Levy, D.* ; Nakamura, Y.* ; Parvez, B.* ; Mahida, S.* ; Furie, K.L.* ; Rosand, J.* ; Muhammad, R.* ; Psaty, B.M.* ; Meitinger, T. ; Perz, S. ; Wichmann, H.-E. ; Witteman, J.C.M.* ; Kao, W.H.L.* ; Kathiresan, S.* ; Roden, D.M.* ; Uitterlinden, A.G.* ; Rivadeneira, F.* ; McKnight, B.* ; Sjögren, M.* ; Newman, A.B.* ; Liu, Y.M.* ; Gollob, M.H.* ; Melander, O.* ; Tanaka, T.* ; Stricker, B.H.C. ; Felix, S.B.* ; Alonso, A.* ; Darbar, D.* ; Barnard, J.* ; Chasman, D.I.* ; Heckbert, S.R.* ; Benjamin, E.J.* ; Gudnason, V.* ; Kääb, S.*
Nat. Genet. 44, 670-675 (2012)
Atrial fibrillation is a highly prevalent arrhythmia and a major risk factor for stroke, heart failure and death(1). We conducted a genome-wide association study (GWAS) in individuals of European ancestry, including 6,707 with and 52,426 without atrial fibrillation. Six new atrial fibrillation susceptibility loci were identified and replicated in an additional sample of individuals of European ancestry, including 5,381 subjects with and 10,030 subjects without atrial fibrillation (P < 5 x 10(-8)). Four of the loci identified in Europeans were further replicated in silico in a GWAS of Japanese individuals, including 843 individuals with and 3,350 individuals without atrial fibrillation. The identified loci implicate candidate genes that encode transcription factors related to cardiopulmonary development, cardiac-expressed ion channels and cell signaling molecules.
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Caballero, M.A.A. ; Rosenthal, A. ; Gateau, J. ; Razansky, D. ; Ntziachristos, V.
Opt. Lett. 37, 4080-4082 (2012)
Optoacoustic (photoacoustic) mesoscopic and microscopic imaging is often implemented by linearly scanning a spherically focused ultrasound transducer. In this case, the resolution and sensitivity along the scan direction are limited by diffraction and therefore degrade rapidly for imaging depths away from the focal point. Partial restoration of the lost resolution can be achieved by using data-processing techniques, such as the virtual detector delay-and-sum method. However, these techniques are based on an approximate description of the detector properties, which limits the improvement in image quality they achieve. Herein we propose a reconstruction method based on an exact model of the optoacoustic generation and propagation that incorporates the spatial response of the sensor. The proposed method shows superior imaging performance over previously considered techniques.
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Scientific Article
Bayer, C.* ; Kielow, A.* ; Schilling, D. ; Maftei, C.A.* ; Zips, D.* ; Yaromina, A.* ; Baumann, M.* ; Molls, M.* ; Multhoff, G.
Int. J. Radiat. Oncol. Biol. Phys. 84, e409-e417 (2012)
PURPOSE: Previous studies have shown that the plasminogen activator inhibitor type-1 (PAI-1) and vascular endothelial growth factor (VEGF) are regulated by hypoxia and irradiation and are involved in neoangiogenesis. The aim of this study was to determine in vivo whether changes in PAI-1 and VEGF during fractionated irradiation could predict for radiation resistance. METHODS AND MATERIALS: Six xenografted tumor lines from human squamous cell carcinomas (HSCC) of the head and neck were irradiated with 0, 3, 5, 10, and 15 daily fractions of 2 Gy. The PAI-1 and VEGF antigen levels in tumor lysates were determined by enzyme-linked immunosorbent assay kits. The amounts of PAI-1 and VEGF were compared with the dose to cure 50% of tumors (TCD(50)). Colocalization of PAI-1, pimonidazole (hypoxia), CD31 (endothelium), and Hoechst 33342 (perfusion) was examined by immunofluorescence. RESULTS: Human PAI-1 and VEGF (hVEGF) expression levels were induced by fractionated irradiation in UT-SCC-15, UT-SCC-14, and UT-SCC-5 tumors, and mouse VEGF (msVEGF) was induced only in UT-SCC-5 tumors. High hVEGF levels were significantly associated with radiation sensitivity after 5 fractions (P=.021), and high msVEGF levels were significantly associated with radiation resistance after 10 fractions (P=.007). PAI-1 staining was observed in the extracellular matrix, the cytoplasm of fibroblast-like stroma cells, and individual tumor cells at all doses of irradiation. Colocalization studies showed PAI-1 staining close to microvessels. CONCLUSIONS: These results indicate that the concentration of tumor-specific and host-specific VEGF during fractionated irradiation could provide considerably divergent information for the outcome of radiation therapy.
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Garcia-Allende, P. ; Amygdalos, I.* ; Dhanapala, H.* ; Goldin, R.D.F.* ; Hanna, G.B.* ; Elson, D.S.*
Proc. SPIE 8213:821328 (2012)
Computer-aided diagnosis of ophthalmic diseases using optical coherence tomography (OCT) relies on the extraction of thickness and size measures from the OCT images, but such defined layers are usually not observed in emerging OCT applications aimed at "optical biopsy" such as pulmonology or gastroenterology. Mathematical methods such as Principal Component Analysis (PCA) or textural analyses including both spatial textural analysis derived from the two-dimensional discrete Fourier transform (DFT) and statistical texture analysis obtained independently from center-symmetric auto-correlation (CSAC) and spatial grey-level dependency matrices (SGLDM), as well as, quantitative measurements of the attenuation coefficient have been previously proposed to overcome this problem. We recently proposed an alternative approach consisting of a region segmentation according to the intensity variation along the vertical axis and a pure statistical technology for feature quantification. OCT images were first segmented in the axial direction in an automated manner according to intensity. Afterwards, a morphological analysis of the segmented OCT images was employed for quantifying the features that served for tissue classification. In this study, a PCA processing of the extracted features is accomplished to combine their discriminative power in a lower number of dimensions. Ready discrimination of gastrointestinal surgical specimens is attained demonstrating that the approach further surpasses the algorithms previously reported and is feasible for tissue classification in the clinical setting.
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Taruttis, A. ; Claussen, J. ; Razansky, D. ; Ntziachristos, V.
J. Biomed. Opt. 17:016009 (2012)
Cardiac imaging in small animals is a valuable tool in basic biological research and drug discovery for cardiovascular disease. Multispectral optoacoustic tomography (MSOT) represents an emerging imaging modality capable of visualizing specific tissue chromophores at high resolution and deep in tissues in vivo by separating their spectral signatures. Whereas single-wavelength images can be acquired by multielement ultrasound detection in real-time imaging, using multiple wavelengths at separate times can lead to image blurring due to motion during acquisition. Therefore, MSOT imaging of the heart results in degraded resolution because of the heartbeat. In this work, we applied a clustering algorithm, k-means, to automatically separate a sequence of single-pulse images at multiple excitation wavelengths into clusters corresponding to different stages of the cardiac cycle. We then performed spectral unmixing on each cluster to obtain images of tissue intrinsic chromophores at different cardiac stages, showing reduced sensitivity to motion compared to signal averaging without clustering. We found that myocardium images of improved resolution and contrast can be achieved using MSOT motion clustering correction. The correction method presented could be generally applied to other MSOT imaging applications prone to motion artifacts, for example, by respiration and heartbeat.
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Burton, N.C. ; Patel, M.* ; Morscher, S. ; Driessen, W.H.P. ; Claussen, J. ; Bézière, N. ; Jetzfellner, T. ; Taruttis, A. ; Razansky, D. ; Bednar, B.* ; Ntziachristos, V.
Neuroimage 15, 522-528 (2012)
Brain research depends strongly on imaging for assessing function and disease in vivo. We examine herein multispectral opto-acoustic tomography (MSOT), a novel technology for high-resolution molecular imaging deep inside tissues. MSOT illuminates tissue with light pulses at multiple wavelengths and detects the acoustic waves generated by the thermoelastic expansion of the environment surrounding absorbing molecules. Using spectral unmixing analysis of the data collected, MSOT can then differentiate the spectral signatures of oxygenated and deoxygenated hemoglobin and of photo-absorbing agents and quantify their concentration. By being able to detect absorbing molecules up to centimeters deep in the tissue it represents an ideal modality for small animal brain imaging, simultaneously providing anatomical, hemodynamic, functional, and molecular information. In this work we examine the capacity of MSOT in cross-sectional brain imaging of mice. We find unprecedented optical imaging performance in cross-sectional visualization of anatomical and physiological parameters of the mouse brain. For example, the potential of MSOT to characterize ischemic brain areas was demonstrated through the use of a carbon dioxide challenge. In addition, indocyanine green (ICG) was injected intravenously, and the kinetics of uptake and clearance in the vasculature of the brain was visualized in real-time. We further found that multiparameter, multispectral imaging of the growth of U87 tumor cells injected into the brain could be visualized through the intact mouse head, for example through visualization of deoxygenated hemoglobin in the growing tumor. We also demonstrate how MSOT offers several compelling features for brain research and allows time-dependent detection and quantification of brain parameters that are not available using other imaging methods without invasive procedures.
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Razansky, D.
IEEE J. Sel. Top. Quantum Electron. 18, 1234-1243 (2012)
Biomedical optoacoustics has emerged in the recent decade as a powerful tool for high-resolution visualization of optical contrast, overcoming a variety of longstanding limitations imposed by light scattering in deep tissues. But true performance of optoacoustic imaging techniques can only be exploited when excitation at multiple wavelengths is used in order to enable highly sensitive spectral differentiation of intrinsic biomarkers and extrinsically administered contrast agents. By detecting tiny sound vibrations, resulting from selective absorption of light at multiple wavelengths, multispectral optoacoustic tomography (MSOT) can now "hear color" in three dimensions, i.e., deliver volumetric spectrally enriched (color) images from deep living tissues at high spatial resolution and in real time. These new-found imaging abilities directly relate to preclinical screening applications in animal models and are foreseen to significantly impact clinical decision making as well. This paper provides the technical essentials of MSOT, including latest developments in the inverse theory, spectral processing algorithms, and imaging instrumentation. Furthermore, a separate section is devoted to the state of the art of molecular imaging applications using MSOT.
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Razansky, D. ; Harlaar, N.J. ; Hillebrands, J.L.* ; Taruttis, A. ; Herzog, E. ; Zeebregts, C.J.* ; van Dam, G.M.* ; Ntziachristos, V.
Mol. Imaging Biol. 14, 277-285 (2012)
Elevated expression of cathepsins, integrins and matrix metalloproteinases (MMPs) is typically associated with atherosclerotic plaque instability. While fluorescent tagging of such molecules has been amply demonstrated, no imaging method was so far shown capable of resolving these inflammation-associated tags with high fidelity and resolution beyond microscopic depths. This study is aimed at demonstrating a new method with high potential for noninvasive clinical cardiovascular diagnostics of vulnerable plaques using high-resolution deep-tissue multispectral optoacoustic tomography (MSOT) technology METHODS AND RESULTS: MMP-sensitive activatable fluorescent probe (MMPSense 680) was applied to human carotid plaques from symptomatic patients. Atherosclerotic activity was detected by tuning MSOT wavelengths to activation-dependent absorption changes of the molecules, structurally modified in the presence of enzymes. MSOT analysis simultaneously provided morphology along with heterogeneous MMP activity with better than 200 micron resolution throughout the intact plaque tissue. The results corresponded well with epi-fluorescence images made from thin cryosections. Elevated MMP activity was further confirmed by in situ zymography, accompanied by increased macrophage influx. CONCLUSIONS: We demonstrated, for the first time to our knowledge, the ability of MSOT to provide volumetric images of activatable molecular probe distribution deep within optically diffuse tissues. High-resolution mapping of MMP activity was achieved deep in the vulnerable plaque of intact human carotid specimens. This performance directly relates to pre-clinical screening applications in animal models and to clinical decision potential as it might eventually allow for highly specific visualization and staging of plaque vulnerability thus impacting therapeutic clinical decision making.
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Omar, M. ; Kellnberger, S. ; Sergiadis, G.* ; Razansky, D. ; Ntziachristos, V.
Proc. SPIE 8223:82231O (2012)
Near-field Radio-frequency Thermoacoustic Imaging (NRTI) is an imaging modality that was recently introduced to generate thermoacoustic signals using ultra-short high energy impulses. Because it allows for a higher energy coupling within an ultra-short time, it can achieve higher resolutions and higher signal to noise ratio, compared to traditional thermoacoustic tomography based on radiating sources at single frequencies. As for traditional thermoacoustic imaging the contrast comes from the conductivity and the dielectric properties of the tissues, while the resolution depends on the measured acoustic waves. Since NRTI depends on the efficient generation of high energy short impulses, the ability to control their time width and pulse shape is of high importance. We present here a methodology for generating such impulses based on transmission lines. The ability of such generators to generate impulses in the range of tens of nanoseconds enables high resolution images in the range of tens of microns to hundreds of microns without compromising the amount of the energy coupled. Finally the pulser is used to generate high resolution images of small absorbing insertions, of phantoms with different conductivities and of ex-vivo mouse images. From the phantoms it is possible to see both the capabilities of the system to accurately image small insertions as well as the high quality images generated from imaging phantoms, from ex-vivo mouse images it is possible to see several anatomical characteristics, such as the mouse boundary, the spine and some other characteristics in the mouse abdomens.
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Omar, M. ; Kellnberger, S. ; Sergiadis, G.* ; Razansky, D. ; Ntziachristos, V.
Med. Phys. 39, 4460-4466 (2012)
Purpose: Near-field radiofrequency thermoacoustic (NRT) tomography has been recently introduced for imaging electromagnetic (EM) properties of tissues using ultrawideband, high-energy impulses, which induce thermoacoustic responses. Operation in the near-field allows for more effective energy coupling into tissue, compared to using radiating sources, which in turn enables the use of shorter excitation pulses and leads to higher image resolution. This work aimed at investigating transmission lines as a method to generate excitation pulses to improve the NRT resolution over previous implementations without compromising the energy coupled into tissue. Methods: The authors implemented a number of custom-made transmission lines to overcome the challenges of the broadband nature of the impulse excitation required in NRT. The authors further constructed phantoms and investigated the performance of the lines in regard to the pulse duration, energy coupling and the resulting resolution, and image quality achieved. Finally, the authors employed mice in order to investigate the performance of the approach in tissue imaging. Results: The authors found that the use of transmission lines resulted in the generation of RF impulses in the range of tens of nanoseconds and shorter. This performance resulted to resolution improvements over previous thermoacoustic imaging implementations, reaching 45 mu m resolution, while retaining several tens to hundreds of milli-Joules of energy per pulse. This performance further allowed the visualization and clear differentiation of different mouse structures such as the heart, lung, or spinal cord. Conclusions: The use of transmission lines significantly improved the NRT performance leading to high thermoacoustic tomography imaging quality by coupling adequate amounts of energy within short times at a relatively low cost.
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Dima, A. ; Ntziachristos, V.
Opt. Express. 20, 25044-25057 (2012)
The high prevalence of atherosclerosis and the corresponding derived morbidity drives the investigation of novel imaging tools for disease diagnosis and assessment. Multi-spectral optoacoustic tomography (MSOT) can resolve structural, hemodynamic and molecular parameters that relate to cardiovascular disease. Similarly to ultrasound imaging, optoacoustic (photoacoustic) imaging can be implemented as a handheld arrangement which further brings dissemination potential to point of care applications. Correspondingly, we experimentally investigate herein the performance of non-invasive optoacoustic scanning developed for carotid imaging, in phantoms and humans. The results demonstrate that traditional transducers employed in ultrasound imaging do not offer optimal MSOT imaging. Instead, feasibility to detect human carotids and carotid-sized vessels in clinically-relevant depths is better demonstrated with curved arrays and tomographic approaches.
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Ma, R. ; Distel, M. ; Dean-Ben, X.L. ; Ntziachristos, V. ; Razansky, D.
Phys. Med. Biol. 57, 7227-7237 (2012)
Zebrafish has emerged as an excellent vertebrate model organism for studies of evolution, development and disease. Due to its external development and optical transparency in embryonic stages, zebrafish offers a major advantage over other vertebrate model organisms by being amenable for microscopic studies of biological processes within their natural environment directly in the living organism. However, commonly used zebrafish strains lose their transparency within their first two weeks of development and thus are no longer accessible for optical imaging approaches at juvenile or adult stages. In this study we successfully apply optoacoustic imaging for non-invasive three-dimensional imaging of adult zebrafish. Since optoacoustics does not necessarily require labeling, but can instead rely on the intrinsic tissue contrast, this imaging method has the potential to become a versatile tool for developmental studies from juvenile to adult stages in the intact zebrafish.
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Schmid, T.E. ; Multhoff, G.
Front. Oncol. 2:80 (2012)
Ionizing irradiation is an important clinical approach to treat solid tumors. Modern radiation technologies aim to selectively kill tumor cells and protect the surrounding normal tissue. The standard paradigm for radiation effects in cellular systems involves damage of the DNA including DNA double-strand breaks, which are considered as most effective in destroying tumor cells. Due to their enhanced physical and radiobiological properties, high-linear energy transfer radiation qualities are of special interest in tumor therapy. Future radiation therapy strategies aim to utilize carbon ions to effectively treat highly aggressive tumors. More recently, evidence is emerging for non-DNA targeted effects of radiation, including mutations, chromosomal aberrations, and changes in gene expression, which can occur in cells that were not directly exposed to radiation. Radiation oncologists are only gradually beginning to appreciate the clinical relevance of radiation-induced bystander effects, genomic instability, and abscopal effects. Since these effects are sensed by the immune system, a combination of immunotherapy and irradiation presents a new therapeutic opportunity in the future.
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Sarantopoulos, A. ; Bézière, N. ; Ntziachristos, V.
Ann. Biomed. Eng. 40, 346-366 (2012)
Many clinical interventional procedures, such as surgery or endoscopy, are today still guided by human vision and perception. Human vision however is not sensitive or accurate in detecting a large range of disease biomarkers, for example cellular or molecular processes characteristic of disease. For this reason advanced optical and opto-acoustic (photo-acoustic) methods are considered for enabling a more versatile, sensitive and accurate detection of disease biomarkers and complement human vision in clinical decision making during interventions. Herein, we outline developments in emerging fluorescence and opto-acoustic sensing and imaging techniques that can lead to practical implementations toward improving interventional vision.
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Herzog, E. ; Taruttis, A. ; Bézière, N. ; Lutich, A.A.* ; Razansky, D. ; Ntziachristos, V.
Radiology 263, 461-468 (2012)
PURPOSE: To investigate whether multispectral optoacoustic tomography (MSOT) can reveal the heterogeneous distributions of exogenous agents of interest and vascular characteristics through tumors of several millimeters in diameter in vivo. MATERIALS AND METHODS: Procedures involving animals were approved by the government of Upper Bavaria. Imaging of subcutaneous tumors in mice was performed by using an experimental MSOT setup that produces transverse images at 10 frames per second with an in-plane resolution of approximately 150 μm. To study dynamic contrast enhancement, three mice with 4T1 tumors were imaged before and immediately, 20 minutes, 4 hours, and 24 hours after systemic injection of indocyanine green (ICG). Epifluorescence imaging was used for comparison. MSOT of a targeted fluorescent agent (6 hours after injection) and hemoglobin oxygenation was performed simultaneously (4T1 tumors: n = 3). Epifluorescence of cryosections served as validation. The accumulation owing to enhanced permeability and retention in tumors (4T1 tumors: n = 4, HT29 tumors: n = 3, A2780 tumors: n = 2) was evaluated with use of long-circulating gold nanorods (before and immediately, 1 hour, 5 hours, and 24 hours after injection). Dark-field microscopy was used for validation. RESULTS: Dynamic contrast enhancement with ICG was possible. MSOT, in contrast to epifluorescence imaging, showed a heterogeneous intratumoral agent distribution. Simultaneous imaging of a targeted fluorescent agent and oxy- and deoxyhemoglobin gave functional information about tumor vasculature in addition to the related agent uptake. The accumulation of gold nanorods in tumors seen at MSOT over time also showed heterogeneous uptake. CONCLUSION: MSOT enables live high-spatial-resolution observations through tumors, producing images of distributions of fluorochromes and nanoparticles as well as tumor vasculature.
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Ale, A.B.F.* ; Ntziachristos, V.
In: (Correct. Techniques in Emission Tomography). 2012. 241-262
Optical imaging refers to imaging techniques that use light as a tool of observation. A large variety of light sources, from visible to near-infrared light, can be used in many different source-detector configurations. This has enabled the development of a wide range of imaging methods and approaches from the macroscopic observation of a patient or an animal to microscopic studies, with numerous applications in clinical practice and biomedical research.
Jin, A.* ; Yazici, B.* ; Ale, A.B.F ; Ntziachristos, V.
Opt. Lett. 37, 4326-4328 (2012)
Image reconstruction in fluorescence diffuse optical tomography (FDOT) is a highly ill-posed inverse problem due to a large number of unknowns and limited measurements. In FDOT, the fluorophore distribution is often sparse in the imaging domain, since most fluorophores are designed to accumulate in relatively small regions. Compressive sensing theory has shown that sparse signals can be recovered exactly from only a small number of measurements when the forward sensing matrix is sufficiently incoherent. In this Letter, we present a method of preconditioning the FDOT forward matrix to reduce its coherence. The reconstruction results using real data obtained from a phantom experiment show visual and quantitative improvements due to preconditioning in conjunction with convex relaxation and greedy-type sparse signal recovery algorithms.
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Multhoff, G. ; Radons, J.*
Front. Oncol. 2:58 (2012)
Chronic inflammation has emerged as one of the hallmarks of cancer. Inflammation also plays a pivotal role in modulating radiation responsiveness of tumors. As discussed in this review, ionizing radiation (IR) leads to activation of several transcription factors modulating the expression of numerous mediators in tumor cells and cells of the microenvironment promoting cancer development. Novel therapeutic approaches thus aim to interfere with the activity or expression of these factors, either in single-agent or combinatorial treatment or as supplements of the existing therapeutic concepts. Among them, NF-κB, STAT-3, and HIF-1 play a crucial role in radiation-induced inflammatory responses embedded in a complex inflammatory network. A great variety of classical or novel drugs including nutraceuticals such as plant phytochemicals have the capacity to interfere with the inflammatory network in cancer and are considered as putative radiosensitizers. Thus, targeting the inflammatory signaling pathways induced by IR offers the opportunity to improve the clinical outcome of radiation therapy by enhancing radiosensitivity and decreasing putative metabolic effects. Since inflammation and sex steroids also impact tumorigenesis, a therapeutic approach targeting glucocorticoid receptors and radiation-induced production of tumorigenic factors might be effective in sensitizing certain tumors to IR.
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Multhoff, G. ; Vaupel, P.*
Front. Oncol. 2:165 (2012)
The immature, chaotic microvasculature of most solid tumors can present a significant impediment to blood-borne delivery, uneven distribution, and compromised penetration of macromolecular anticancer drugs and diagnostic agents from tumor microvessels across the interstitial space to cancer cells. To reach viable tumor cells in relevant concentrations, macromolecular agents are confronted with several barriers to vascular, transvascular, and interstitial transport. Amongst those (1) heterogeneous and poor blood supply, (2) distinctly reduced or even abolished hydrostatic and oncotic pressure gradients across the microvessel wall abrogating the convective transport from the vessel lumen into the interstitial space (impairment of transvascular transport), and (3) impediment of convective transport within the interstitial compartment due to elevated interstitial fluid pressure (IFP) (resulting from hyperpermeable blood vessels coupled with non-functional lymphatics) and a dense structure of the interstitial matrix are the major mechanisms hindering drug delivery. Upon irradiation, changes in these barrier functions are inconclusive so far. Alterations in vascular transport properties following fractionated radiation up to 40 Gy are quite inconsistent in terms of direction, extent, and time course. Total doses above 45 Gy can damage tumor microvessels, additionally impeding vascular delivery. Vascular permeability for macromolecules might be enhanced up to a total dose of 45 Gy. However, this effect is counteracted/abolished by the elevated IFP in solid tumors. When assessing IFP during fractionated radiotherapy in patient tumors, inconsistent alterations have been observed, both in direction and extent. From these data it is concluded that modulations in vascular, transvascular, and interstitial transport by irradiation of solid tumors are rather unclear so far. Translation of experimental data into the clinical setting thus needs to be undertaken with especial care.
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Schmid, T.E.* ; Multhoff, G.
Curr. Med. Chem. 19, 1765-1770 (2012)
ogether with surgery and chemotherapy, ionizing irradiation is one of the key therapeutic approaches to treat cancer. More than 50 percent of all cancer patients will receive radiotherapeutic intervention at some stage of their disease. The more precise instrumentation for delivery of radiotherapy and the emphasis on hypofractionation technologies have drastically improved loco-regional tumor control within the last decades. However, the appearance of distant metastases often requires additional systemic treatment modalities such as chemotherapy. High dose chemotherapy is generally considered as immunosuppressive and can cause severe adverse effects. Therefore, we want to elucidate the effects of ionizing irradiation on the immune system and provide immunological treatment strategies which are induced by the host's stress response. Similar to other stressors, ionizing irradiation is known to enhance the synthesis of a variety of immune-stimulatory and -modulating molecules such as heat shock proteins (HSP), high mobility group box 1 (HMGB1) and survivin. Herein, we focus on HSP that exhibit an unusual cell membrane localization and release mechanism in tumor cells. These tumor-specific characteristics render HSP as ideal targets for therapeutic interventions. Depending on their intra/membrane and extracellular localization HSP have the ability to protect tumor cells from stress-induced lethal damage by interfering with antiapoptotic pathways or to elicit anti-cancer immunity.
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Schilling, D.* ; Bayer, C.* ; Li, W.* ; Molls, M.* ; Vaupel, P.* ; Multhoff, G.
PLoS ONE 7:e31110 (2012)
BACKGROUND: Ionizing irradiation is a commonly accepted treatment modality for lung cancer patients. However, the clinical outcome is hampered by normal tissue toxicity and tumor hypoxia. Since tumors often have higher levels of active heat shock protein 90 (Hsp90) than normal tissues, targeting of Hsp90 might provide a promising strategy to sensitize tumors towards irradiation. Hsp90 client proteins include oncogenic signaling proteins, cell cycle activators, growth factor receptors and hypoxia inducible factor-1α (HIF-1α). Overexpression of HIF-1α is assumed to promote malignant transformation and tumor progression and thus might reduce the accessibility to radiotherapy. METHODOLOGY/PRINCIPAL FINDINGS: Herein, we describe the effects of the novel Hsp90 inhibitor NVP-AUY922 and 17-allylamino-17-demethoxygeldanamycin (17-AAG), as a control, on HIF-1α levels and radiosensitivity of lung carcinoma cells under normoxic and hypoxic conditions. NVP-AUY922 exhibited a similar biological activity to that of 17-AAG, but at only 1/10 of the dose. As expected, both inhibitors reduced basal and hypoxia-induced HIF-1α levels in EPLC-272H lung carcinoma cells. However, despite a down-regulation of HIF-1α upon Hsp90 inhibition, sensitivity towards irradiation remained unaltered in EPLC-272H cells under normoxic and hypoxic conditions. In contrast, treatment of H1339 lung carcinoma cells with NVP-AUY922 and 17-AAG resulted in a significant up-regulation of their initially high HIF-1α levels and a concomitant increase in radiosensitivity. CONCLUSIONS/SIGNIFICANCE: In summary, our data show a HIF-1α-independent radiosensitization of normoxic and hypoxic H1339 lung cancer cells by Hsp90 inhibition.
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Rodriguez-Cobo, L.* ; Garcia-Allende, P. ; Cobo, A.* ; Lopez-Higuera, J.M.* ; Conde, O.M.*
IEEE Sens. J. 12, 2767-2775 (2012)
The recently proposed hierarchical temporal memory (HTM) paradigm of soft computing is applied to the detection and classification of foreign materials in a conveyor belt carrying tobacco leaves in a cigarette manufacturing industry. The HTM has been exposed to hyperspectral imaging data from 10 types of unwanted materials intermingled with tobacco leaves. The impact of the HTM architecture and the configuration of internal parameters on its classification performance have been explored. Classification results match or surpass those attained with other methods, such as Artificial Neural Networks (ANNs), with the advantage that HTM are able to handle raw spectral data and no preprocessing, spectral compression, or reflectance correction is required. It is also demonstrated that an optimized configuration of the HTM architecture and internal values can be derived from the statistical properties of the hyperspectral data, allowing the extension of the approach to other classification problems.
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Morscher, S.* ; Burton, N.C. ; Taruttis, A. ; Deliolanis, N.C. ; Razansky, D. ; Ntziachristos, V.
Proc. SPIE 8223:822330 (2012)
Multi-Spectral Optoacoustic Tomography (MSOT) offers real time imaging that simultaneously exploits high ultrasound resolutions and strong optical contrast. It allows visualizing absorbers in tissue by using their distinct spectral absorption profiles. This work presents a non-invasive in vivo study of kinetics involved in the clearance of carboxylated dye in mouse kidneys
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Voss, A.* ; Heitmann, A.* ; Schroeder, R.* ; Peters, A. ; Perz, S.
Physiol. Meas. 33, 1289-1311 (2012)
Heart rate variability (HRV) analysis is an established method to characterize the autonomic regulation and is based mostly on 24h Holter recordings. The importance of short-term HRV (less than 30 min) for various applications is growing consistently. Major reasons for this are the suitability for ambulatory care and patient monitoring and the ability to provide an almost immediate test result. So far, there have been only a few studies that provided statistically relevant reference values for short-term HRV. In our study, 5 min short-term HRV indices were determined from 1906 healthy subjects. From these records, linear and nonlinear indices were extracted. To determine general age-related influences, HRV indices were compared from subjects aged 25-49 years with subjects aged 50-74 years. In a second approach, we examined the development of HRV indices by age in terms of age decades (25-34, 35-44, 45-54, 55-64 and 65-74 years). Our results showed significant variations of HRV indices by age in almost all domains. While marked dynamics in terms of parameter change (variability reduction) were observed in the first age decades, in particular the last two age decades showed certain constancy with respect to the HRV indices examined.
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Nagaraja, G.M.* ; Kaur, P.* ; Neumann, W.* ; Asea, E.E.* ; Bausero, M.A.* ; Multhoff, G. ; Asea, A.*
Cancer Prev. Res. 5, 122-137 (2012)
Relatively high expression of Hsp27 in breast and prostate cancer is a predictor of poor clinical outcome. This study elucidates a hitherto unknown mechanism by which Hsp27 regulates proteasome function and modulates tumor-specific T-cell responses. Here, we showed that short-term silencing of Hsp25 or Hsp27 using siRNA or permanent silencing of Hsp25 using lentivirus RNA interference technology enhanced PA28α mRNA expression, PA28α protein expression, and proteasome activity; abrogated metastatic potential; induced the regression of established breast tumors by tumor-specific CD8(+) T cells; and stimulated long-lasting memory responses. The adoptive transfer of reactive CD8(+) T cells from mice bearing Hsp25-silenced tumors efficiently induced the regression of established tumors in nontreated mice which normally succumb to tumor burden. The overexpression of Hsp25 and Hsp27 resulted in the repression of normal proteasome function, induced poor antigen presentation, and resulted in increased tumor burden. Taken together, this study establishes a paradigm shift in our understanding of the role of Hsp27 in the regulation of proteasome function and tumor-specific T-cell responses and paves the way for the development of molecular targets to enhance proteasome function and concomitantly inhibit Hsp27 expression in tumors for therapeutic gain.
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Rosenthal, A. ; Caballero, M.A.A. ; Kellnberger, S. ; Razansky, D. ; Ntziachristos, V.
Opt. Lett. 37, 3174-3176 (2012)
Optical fibers have long been recognized as a promising technology for remote sensing of ultrasound. Nonetheless, very little is known about the characteristics of their spatial response, which is significantly affected by the strong acoustic mismatches between the fiber and surrounding medium. In this Letter, a new method is demonstrated for wideband spatial acoustic characterization of optical fibers. The method is based on the excitation of a point-like acoustic source via the opto-acoustic effect, while a miniature fiber sensor is implemented by a p-phase-shifted fiber Bragg grating. Despite the relative complexity of acoustic wave propagation in the fiber, its spatial sensitivity in the high frequency band (6-30 MHz) exhibited an orderly pattern, which can be described by a simple model. This property reveals new possibilities for high-performance imaging using fiber-based ultrasound sensors, where knowledge of the sensor's spatial sensitivity map is generally required.
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Kopanitsa, G.
Stud. Health Technol. Inform. 180, 199-203 (2012)
An efficient interaction between a doctor and an electronic health record (EHR) depends also on the visual layer of an EHR. As users with various backgrounds and needs have different perspectives on the same data visualization methods must be flexible to provide the optimal interface. The ISO 13606 community is interested in developing requirements on a generic visualization method that can supplement the archetype model. Our research aims at specifying the requirements on a medical data visualization method based on the ISO13606 data model. XML allows a clear structuring and validation of the data due to the built-in standard features. The proposed visual medical concept allows separating the medical knowledge from the visualization knowledge. The research is focused defining the optimal XML schema for a visual medical concept to allow multiclient generic data presentation.
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Scientific Article
Veseli, H. ; Demski, H. ; Hildebrand, C.
In: Schreier, G.* ; Hayn, D.* ; Hörbst, A.* ; Ammenwerth, E.* [Eds.]: Proceedings (eHealth2012, 2012 Mai 10-11; Vienna, Austria). Wien: AIT Austrian Institute of Technology, 2012. 83-88 ( ; Proceedings of the eHealth2012)
Semantische Interoperabilität von EHR (Elektronischen Krankenakten) ist eine wesentliche Herausforderung in der Medizinischen Informatik. In der vorgestellten Lösung werden die Kommunikationsbarrieren, die durch heterogene EHR-Systeme verursacht werden, in einem regionalen Ärztenetzwerk in Deutschland veranschaulicht. EHR-Interoperabilität wird durch ein kanonisches Modell klinischer Daten ermöglicht, die auf ISO 13606 und ASTM CCR basieren. Ein Kommunikationsserver stellt Schnittstellen bereit, die dem Stand der Technik entsprechen, und bietet Zugriffsmöglichkeiten auch für die EHR-Systeme, die nicht modernen Interoperabilitätsanforderungen genügen, um eine hohe Teilnehmerzahl zu gewährleisten. Der Server bietet weiterhin einen Mehrwert durch Visualisierungs-Features, die den Abruf der übermittelten Daten in verschiedenen Darstellungsvarianten ermöglichen.
Veseli, H. ; Kopanitsa, G. ; Demski, H.
In: Mantas, J.* ; Andersen, S.K.* ; Mazzoleni, M.C.* ; Blobel, B.* ; Quaglini, S.* ; Moen, A.* [Eds.]: Quality of Life through Quality of Information (MIE 2012, The XXIVst International Congress of the European Federation for Medical Informatics). Amsterdam: IOS Press, 2012. 646-650 (Stud. Health Technol. Inform. ; 180)
The mobility of doctors and patients asks for multilingualism of electronic health record (EHR) systems: Doctors might face language problems using foreign medical information systems; people working abroad ask for continuous care which requires the treating physician to consult and understand the patient's health record. To address these linguistic and interoperability issues a solution is being developed that is based on widely acclaimed standards. Medical concepts that are derived from ASTM CCR define an interface model (based on ISO 13606). A server manages the data exchange between heterogeneous systems based on the interface model. It provides web services (automatic) and web forms (manual) and performs a transformation from the legacy scheme to the common structure. Furthermore, the server provides rich visualization capabilities (e.g. language-switch, custom charts etc.) which are useful for those EHR systems that don't provide these features.
Mohajer, M. ; Schmid, V.J.* ; Engels, N. A.* ; Noel, P. B.* ; Rummeny, E.* ; Englmeier, K.-H.
Proc. SPIE 8317:83171K (2012)
The signal curves in perfusion dynamic contrast enhanced MRI (DCE-MRI) of cancerous breast tissue reveal valuable information about tumor angiogenesis. Pathological studies have illustrated that breast tumors consist of different subregions, especially with more homogeneous properties during their growth. Differences should be identifiable in DCEMRI signal curves if the characteristics of these sub-regions are related to the perfusion and angiogenesis. We introduce a stepwise clustering method which in a first step uses a new similarity measure. The new similarity measure (PM) compares how parallel washout phases of two curves are. To distinguish the starting point of the washout phase, a linear regression method is partially fitted to the curves. In the next step, the minimum signal value of the washout phase is normalized to zero. Finally, PM is calculated according to maximal variation among the point wise differences during washout phases. In the second step of clustering the groups of signal curves with parallel washout are clustered using Euclidean distance. The introduced method is evaluated on 15 DCE-MRI breast datasets with different types of breast tumors. The use of our new heterogeneity analysis is feasible in single patient examination and improves breast MR diagnostics.
Wissenschaftlicher Artikel
Scientific Article
Demski, H. ; Hildebrand, C. ; López Bolós, J. ; Tiedge, W.* ; Wengel, S.* ; O Broin, D.* ; Palmer, R.*
In: Mantas, J.* ; Andersen, S.K.* ; Mazzoleni, M.C.* ; Blobel, B.* ; Quaglini, S.* ; Moen, A.* [Eds.]: Quality of Life through Quality of Information (MIE 2012, The XXIVst International Congress of the European Federation for Medical Informatics). Amsterdam: IOS Press, 2012. 818-822 (Stud. Health Technol. Inform. ; 180)
Feeling an integrative part of a social community adds to the quality of life. Elderly people who find it more difficult to actively join activities are often threatened by isolation. Social networking can enable communication and sharing activities makes it easier to set up and maintain contacts. This paper describes the development of a social networking platform and activities like gaming and exergaming all of which aim to facilitate social interaction. It reports on the particular challenges that need to be addressed when creating a social networking platform specially designed to meet the needs of the elderly.
Eguizabal, A.* ; Laughney, A.M.* ; Garcia-Allende, P. ; Krishnaswamy, V.* ; Wells, W.A.* ; Paulsen, K.D.* ; Pogue, B.W.* ; Lopez-Higuera, J.M.* ; Conde, O.M.:*
In: Proceedings of the 9th IEEE International Symposium on Biomedical Imaging (From Nano to Macro ISBI 2012, Barcelona, 2-5 May 2012). Piscataway, NJ: IEEE, 2012. 1615-1618
Textural analysis of tissue scattering images is proposed for healthy versus tumor discrimination. Scattering center density varies from normal to tumor tissues and this variation is translated into different textures in the scattering power map. Adipose tissue shows low autocorrelation values while tumor tissues present higher entropies than normal tissue. Consequently, a combination of autocorrelation and entropy values allows ready tissue discrimination by a supervised linear classifier. The proposed approach has been validated over a set of 29 breast tissue samples achieving a sensitivity of 73.59% and specificity of 82.40%.
Bühler, A. ; Dean-Ben, X.L. ; Claussen, J. ; Ntziachristos, V. ; Razansky, D.
Opt. Express. 20, 22712-22719 (2012)
Using optoacoustic excitation, a complete volumetric tomographic data sets from the imaged object can in principle be generated with a single interrogating laser pulse. Thus, optoacoustic imaging intrinsically has the potential for fast three-dimensional imaging. We have developed a system capable of acquiring volumetric optoacoustic data in real time and showcase in this work the undocumented capacity to generate high resolution three-dimensional optoacoustic images at a rate of 10Hz, currently mainly limited by the pulse repetition rate of the excitation laser.
Wissenschaftlicher Artikel
Scientific Article
Knaup-Gregori, P.* ; Schöpe, L.* ; Demski, H. ; Ganzinger, M.* ; Hanning, R.* ; Helmer, A.* ; Jankowski, A.* ; Kraft, A.* ; Kolly, L.* ; Kröger, R.* ; Plischke, M.* ; Schäfer, J.* ; Schöchlin, J.* ; Spitalewsky, K.* ; Soltani, N.* ; Stiller, C.* ; Storf, H.* ; Thoss, M.* ; Ulrich, S.*
Berlin: VDE Verl., 2012. 96 S.
Der erwartete demografische Wandel wird einen erheblichen Einfluss auf die Gesellschafts- und Sozialstrukturen der Industrieländer haben. Technische Komponenten im Sinne des Ambient Assisted Living (AAL) sollen dazu beitragen, dass ältere Menschen unter anderem länger im häuslichen Umfeld verbleiben können und auch länger mobil und trotzdem gut versorgt sind. Betrachtet man die Vielzahl der Daten, die durch AAL-Anwendungen generiert werden, so wird deutlich, dass sich ein großes Potenzial für die Lebensgestaltung der Betroffenen und ihres persönlichen Umfelds ergibt, wenn diese Daten sorgfältig verdichtet und zielgerichtet ausgewertet werden. Derartige Aufgabenstellungen gehen weit über eine rein technische Unterstützung, die das Ziel hat, Notfallsituationen zu erkennen und zu vermeiden, hinaus. So können die Daten bei einer geeigneten Weiterverarbeitung zur Früherkennung von gesundheitlichen Problemen und zur Prävention genutzt werden. Daher ist neben der AAL-Technik auch die für die systematische Informationsverarbeitung benötigte Technik, die Informationstechnologie (IT), von großer Bedeutung. Die Informatik als Wissenschaft von der systematischen Verarbeitung von Informationen kann die Entwicklung von AAL-Lösungen wesentlich unterstützen, damit Daten über einen längeren Zeitraum archiviert, ausgewertet und bereitgestellt werden können. Nach Ansicht der AG IT liegt das Potenzial einer systematischen Informationsverarbeitung im AAL-Umfeld in einer größeren Nachhaltigkeit, besseren Technologieakzeptanz, Sicherheit, Robustheit, Anpassbarkeit und besseren Integration in vorhandene Strukturen. Dieses Potenzial wird derzeit längst noch nicht voll ausgeschöpft und nicht zielgerichtet gefördert. Betrachtet man die bisher geförderten Projekte im Bereich AAL so kann man feststellen, dass die Sensor-Entwicklung deutlich stärker im Vordergrund stand als das Informationsmanagement. Daraus resultieren viele innovative Produkte, aber nur wenige innovative Prozesse. In vielen Projekten werden einzelne IT-Komponenten entwickelt, die zu Modellprojekten oder Insellösungen führen. Damit AAL wirklich eine Erfolgsgeschichte und die zugehörige Technik verbreitet genutzt werden kann, bedarf es der Forschung auf dem Gebiet des Informations- und Prozessmanagements. Dazu gehört sowohl die geeignete Integration von AAL-Komponenten und innovativen Informationssystemen in vorhandene Prozesse und Strukturen als auch die Etablierung von neuen Prozessen und Strukturen. Der Aufwand hierfür darf nicht unterschätzt werden, insbesondere weil Informationssysteme auch soziotechnische Systeme sind. Die technischen AAL-Komponenten können nicht getrennt von sozialen, ethischen und moralischen Aspekten betrachtet werden. Neben der Mensch-Maschine-Interaktion und der ambienten Assistenz ist die zwischenmenschliche Kommunikation von wesentlicher Bedeutung. Dies relativiert gerade bei AAL-Systemen immer wieder die technische Machbarkeit. Aktuelle Entwicklungen im Bereich AAL müssen sich stark an den Bedürfnissen der Nutzer orientieren. Hier sehen die Autoren des Positionspapiers einen erheblichen, vielschichtigen Forschungsbedarf.
Rosenthal, A. ; Kellnberger, S. ; Sergiadis, G.* ; Ntziachristos, V.
IEEE Photonics Technol. Lett. 24 (2012)
We report on a robust scheme for wideband variable-phase interferometer stabilization based on active modulation. In contrast to previous schemes, the correction signal is generated without using second harmonics, whose low amplitude often requires employing narrowband lock-in amplifiers. Resonances in the element modulating the phase are attenuated to enable high gain without high-frequency oscillations. Operation over a 3-kHz bandwidth is demonstrated.
Wissenschaftlicher Artikel
Scientific Article
Rosenthal, A. ; Razansky, D. ; Ntziachristos, V.
Opt. Express. 20, 19016-19029 (2012)
Advances in fabrication of high-finesse optical resonators hold promise for the development of miniaturized, ultra-sensitive, wide-band optical sensors, based on resonance-shift detection. Many potential applications are foreseen for such sensors, among them highly sensitive detection in ultrasound and optoacoustic imaging. Traditionally, sensor interrogation is performed by tuning a narrow linewidth laser to the resonance wavelength. Despite the ubiquity of this method, its use has been mostly limited to lab conditions due to its vulnerability to environmental factors and the difficulty of multiplexing - a key factor in imaging applications. In this paper, we develop a new optical-resonator interrogation scheme based on wideband pulse interferometry, potentially capable of achieving high stability against environmental conditions without compromising sensitivity. Additionally, the method can enable multiplexing several sensors. The unique properties of the pulse-interferometry interrogation approach are studied theoretically and experimentally. Methods for noise reduction in the proposed scheme are presented and experimentally demonstrated, while the overall performance is validated for broadband optical detection of ultrasonic fields. The achieved sensitivity is equivalent to the theoretical limit of a 6 MHz narrow-line width laser, which is 40 times higher than what can be usually achieved by incoherent interferometry for the same optical resonator.
Wissenschaftlicher Artikel
Scientific Article

2011

Calfon, M.A.* ; Rosenthal, A. ; Mallas, G.* ; Mauskapf, A.* ; Nudelman, R.N. ; Ntziachristos, V. ; Jaffer, F.A.*
J. Vis. Exp. 54:e2257 (2011)
The vascular response to injury is a well-orchestrated inflammatory response triggered by the accumulation of macrophages within the vessel wall leading to an accumulation of lipid-laden intra-luminal plaque, smooth muscle cell proliferation and progressive narrowing of the vessel lumen. The formation of such vulnerable plaques prone to rupture underlies the majority of cases of acute myocardial infarction. The complex molecular and cellular inflammatory cascade is orchestrated by the recruitment of T lymphocytes and macrophages and their paracrine effects on endothelial and smooth muscle cells.(1) Molecular imaging in atherosclerosis has evolved into an important clinical and research tool that allows in vivo visualization of inflammation and other biological processes. Several recent examples demonstrate the ability to detect high-risk plaques in patients, and assess the effects of pharmacotherapeutics in atherosclerosis.(4) While a number of molecular imaging approaches (in particular MRI and PET) can image biological aspects of large vessels such as the carotid arteries, scant options exist for imaging of coronary arteries.(2) The advent of high-resolution optical imaging strategies, in particular near-infrared fluorescence (NIRF), coupled with activatable fluorescent probes, have enhanced sensitivity and led to the development of new intravascular strategies to improve biological imaging of human coronary atherosclerosis. Near infrared fluorescence (NIRF) molecular imaging utilizes excitation light with a defined band width (650-900 nm) as a source of photons that, when delivered to an optical contrast agent or fluorescent probe, emits fluorescence in the NIR window that can be detected using an appropriate emission filter and a high sensitivity charge-coupled camera. As opposed to visible light, NIR light penetrates deeply into tissue, is markedly less attenuated by endogenous photon absorbers such as hemoglobin, lipid and water, and enables high target-to-background ratios due to reduced autofluorescence in the NIR window. Imaging within the NIR 'window' can substantially improve the potential for in vivo imaging.(2,5) Inflammatory cysteine proteases have been well studied using activatable NIRF probes(10), and play important roles in atherogenesis. Via degradation of the extracellular matrix, cysteine proteases contribute importantly to the progression and complications of atherosclerosis(8). In particular, the cysteine protease, cathepsin B, is highly expressed and colocalizes with macrophages in experimental murine, rabbit, and human atheromata.(3,6,7) In addition, cathepsin B activity in plaques can be sensed in vivo utilizing a previously described 1-D intravascular near-infrared fluorescence technology(6), in conjunction with an injectable nanosensor agent that consists of a poly-lysine polymer backbone derivatized with multiple NIR fluorochromes (VM110/Prosense750, ex/em 750/780nm, VisEn Medical, Woburn, MA) that results in strong intramolecular quenching at baseline.(10) Following targeted enzymatic cleavage by cysteine proteases such as cathepsin B (known to colocalize with plaque macrophages), the fluorochromes separate, resulting in substantial amplification of the NIRF signal. Intravascular detection of NIR fluorescence signal by the utilized novel 2D intravascular NIRF catheter now enables high-resolution, geometrically accurate in vivo detection of cathepsin B activity in inflamed plaque. In vivo molecular imaging of atherosclerosis using catheter-based 2D NIRF imaging, as opposed to a prior 1-D spectroscopic approach,(6) is a novel and promising tool that utilizes augmented protease activity in macrophage-rich plaque to detect vascular inflammation. (11,12) The following research protocol describes the use of an intravascular 2-dimensional NIRF catheter to image and characterize plaque structure utilizing key aspects of plaque biology. It is a translatable platform that when integrated with existing clinical imaging technologies including angiography and intravascular ultrasound (IVUS), offers a unique and novel integrated multimodal molecular imaging technique that distinguishes inflammatory atheromata, and allows detection of intravascular NIRF signals in human-sized coronary arteries.
Wissenschaftlicher Artikel
Scientific Article
Deliolanis, N.C. ; Wurdinger, T.* ; Pike, L.* ; Tannous, B.A.* ; Breakefield, X.O.* ; Weissleder, R.* ; Ntziachristos, V.
Biomed. Opt. Express 2, 887-900 (2011)
We have developed a spectral inversion method for three-dimensional tomography of far-red and near-infrared fluorescent proteins in animals. The method was developed in particular to address the steep light absorption transition of hemoglobin from the visible to the far-red occurring around 600 nm. Using an orthotopic mouse model of brain tumors expressing the red-shifted fluorescent protein mCherry, we demonstrate significant improvements in imaging accuracy over single-wavelength whole body reconstructions. Furthermore, we show an improvement in sensitivity of at least an order of magnitude over green fluorescent protein (GFP) for whole body imaging. We discuss how additional sensitivity gains are expected with the use of further red-shifted fluorescent proteins and we explain the differences and potential advantages of this approach over two-dimensional planar imaging methods.
Wissenschaftlicher Artikel
Scientific Article
Mohajer, M.* ; Engels, N.* ; Noel, P.* ; Rummeny, E.* ; Englmeier, K.-H.
In: Proceedings (European Society for Magnetic Resonance in Medicine and Biology (ESMRMB), 28th Annual Scientific Meeting, Leipzig, Germany). 2011. 296
Glatz, J. ; Deliolanis, N.C. ; Bühler, A. ; Razansky, D. ; Ntziachristos, V.
Opt. Express. 19, 3175-3184 (2011)
Multispectral optoacoustic (photoacoustic) tomography (MSOT) is a hybrid modality that can image through several millimeters to centimeters of diffuse tissues, attaining resolutions typical of ultrasound imaging. The method can further identify tissue biomarkers by decomposing the spectral contributions of different photo-absorbing molecules of interest. In this work we investigate the performance of blind source unmixing methods and spectral fitting approaches in decomposing the contributions of fluorescent dyes from the tissue background, based on MSOT measurements in mice. We find blind unmixing as a promising method for accurate MSOT decomposition, suitable also for spectral unmixing in fluorescence imaging. We further demonstrate its capacity with temporal unmixing on real-time MSOT data obtained in-vivo for enhancing the visualization of absorber agent flow in the mouse vascular system.
Wissenschaftlicher Artikel
Scientific Article
Morscher, S. ; Glatz, J. ; Deliolanis, N. ; Bühler, A. ; Razansky, D. ; Ntziachristos, V.
Proc. SPIE 7899:78993D (2011)
Multispectral optoacoustic (photoacoustic) tomography (MSOT) exploits the high resolutions provided by ultrasound imaging technology in combination with the more biologically relevant optical absorption contrast. Traces of molecules with different spectral absorption profiles, such as blood (oxy- and de-oxygenated) and biomarkers can be recovered using multiple wavelengths excitation and a set of methods described in this work. Three unmixing methods are examined for their performance in decomposing images into components in order to locate fluorescent contrast agents in deep tissue in mice. Following earlier works we find Independent Component Analysis (ICA), which relies on the strong criterion of statistical independence of components, as the most promising approach, being able to clearly identify concentrations that other approaches fail to see. The results are verified by cryosectioning and fluorescence imaging.
Wissenschaftlicher Artikel
Scientific Article
Rosenthal, A. ; Ntziachristos, V. ; Razansky, D.
Proc. SPIE 7899:78992L (2011)
Ultrasonic detectors are commonly calibrated by finding their response to incident plane waves. However, in optoacoustics, the response to broadband point sources is required. To induce such sources using the optoacoustic effect, the illuminated object's dimensions must be smaller than the resolution achievable by the optoacoustic system. The main difficulty in such measurements is that the magnitude of the field emitted by such sources is proportional to their dimensions, and thus may be weak compared to parasitic sources in the setup. In this work we experimentally demonstrate two methods for calibrating acoustic detectors. In both methods, acoustic sources are optoacoustically induced in large optically absorbing slabs. Despite the large dimensions of the illuminated objects, the geometry used yields wide-band acoustic fields, which are perceived by the detectors as originating from point sources.
Wissenschaftlicher Artikel
Scientific Article
Ntziachristos, V.
Philos. Trans. R. Soc. A - Math. Phys. Eng. Sci. 369, 4666-4678 (2011)
Macroscopic optical imaging has rather humble technical origins; it has been mostly implemented by photographic means using appropriate filters, a light source and a camera yielding images of tissues. This approach relates to human vision and perception, and is simple to implement and use. Therefore, it has found wide acceptance, especially in recording fluorescence and bioluminescence signals. Yet, the difficulty in resolving depth and the dependence of the light intensity recorded on tissue optical properties may compromise the accuracy of the approach. Recently, optical technology has seen significant advances that bring a new performance level in optical investigations. Quantitative real-time multi-spectral optical and optoacoustic (photoacoustic) methods enable high-resolution quantitative imaging of tissue and disease biomarkers and can significantly enhance medical vision in diagnostic or interventional procedures such as dermatology, endoscopy, surgery, and various vascular and intravascular imaging applications. This performance is showcased herein and examples are given to illustrate how it is possible to shift the paradigm of optical clinical translation.
Wissenschaftlicher Artikel
Scientific Article
Dean-Ben, X.L. ; Razansky, D. ; Ntziachristos, V.
Proc. SPIE 8090:809014 (2011)
The feasibility of correcting for the effects of acoustic attenuation in optoacoustic tomographic reconstructions obtained with model-based inversion is shown in this work. Acoustic attenuation is a physical phenomenon that takes place inevitably in actual acoustic media and becomes significant at high ultrasonic frequencies. The frequency dependence of acoustic attenuation and the associated dispersion lead to reduction of amplitude and broadening of the optoacoustic signals, which in turn cause, respectively, quantification errors and loss of resolution in the reconstructed images. In this work we imaged an agar phantom with embedded microparticles in three different scenarios, namely with the signals acquired with no attenuation, with the signals collected by placing an attenuating sample in between the phantom and the ultrasonic transducer and with the signals corrected for the effects of acoustic attenuation. The results obtained show that the quantification inaccuracies and the loss of resolution of the images can be partially corrected at the expense of introducing noise at high spatial frequencies due to the amplification of the high frequency components of the noise in the signals.
Wissenschaftlicher Artikel
Scientific Article
Stangl, S. ; Themelis, G. ; Friedrich, L.* ; Ntziachristos, V. ; Sarantopoulos, A. ; Molls, M. ; Skerra, A.* ; Multhoff, G.
Radiother. Oncol. 99, 313-316 (2011)
The major stress-inducible heat shock protein 70 (Hsp70) is frequently overexpressed in highly aggressive tumors, and elevated intracellular Hsp70 levels mediate protection against apoptosis. Following therapeutic intervention, such as ionizing irradiation, translocation of cytosolic Hsp70 to the plasma membrane is selectively increased in tumor cells and therefore, membrane Hsp70 might serve as a therapy-inducible, tumor-specific target structure. MATERIALS AND METHODS: Based on the IgG1 mouse monoclonal antibody (mAb) cmHsp70.1, we produced the Hsp70-specific recombinant Fab fragment (Hsp70 Fab), as an imaging tool for the detection of membrane Hsp70 positive tumor cells in vitro and in vivo. RESULTS: The binding characteristics of Hsp70 Fab towards mouse colon (CT26) and pancreatic (1048) carcinoma cells at 4°C were comparable to that of cmHsp70.1 mAb, as determined by flow cytometry. Following a temperature shift to 37°C, Hsp70 Fab rapidly translocates into subcellular vesicles of mouse tumor cells. Furthermore, in tumor-bearing mice Cy5.5-conjugated Hsp70 Fab, but not unrelated IN-1 control Fab fragment (IN-1 ctrl Fab), gradually accumulates in CT26 tumors between 12 and 55h after i.v injection.CONCLUSIONS: In summary, the Hsp70 Fab provides an innovative, low immunogenic tool for imaging of membrane Hsp70 positive tumors, in vivo.
Wissenschaftlicher Artikel
Scientific Article
Razansky, D. ; Rozental, A.* ; Müller, M.S.* ; Deliolanis, N. ; Jaffer, F.A.* ; Koch, A.W.* ; Ntziachristos, V.
Proc. SPIE 7894:78940K (2011)
Early detection of high-risk coronary atherosclerosis remains an unmet clinical challenge. We have previously demonstrated a near-infrared fluorescence catheter system for two-dimensional intravascular detection of fluorescence molecular probes [1]. In this work we improve the system performance by introducing a novel high resolution sensor. The main challenge of the intravascular sensor is to provide a highly focused spot at an application relevant distance on one hand and a highly efficient collection of emitted light on the other. We suggest employing a double cladding optical fiber (DCF) in combination with focusing optics to provide a sensor with both highly focused excitation light and highly efficient fluorescent light collection. The excitation laser is coupled into the single mode core of DCF and guided through a focusing element and a right angle prism. The resulting side-fired beam exhibits a small spot diameter (50 μm) throughout a distance of up to 2 mm from the sensor. This is the distance of interest for intravascular coronary imaging application, determined by an average human coronary artery diameter. At the blood vessel wall, an activatable fluorescence molecular probe is excited in the diseased lesions. Next light of slightly shifted wavelength emits only in the places of the inflammations, associated with dangerous plaques [2]. The emitted light is collected by the cladding of the DCF, with a large collection angle (NA=0.4). The doublecladding acts as multimodal fiber and guides the collected light to the photo detection elements. The sensor automatically rotates and pulled-back, while each scanned point is mapped according to the amount of detected fluorescent emission. The resulting map of fluorescence activity helps to associate the atherosclerotic plaques with the inflammation process. The presented detection system is a valuable tool in the intravascular plaque detection and can help to differentiate the atherosclerotic plaques based on their biological activity, identify the ones that prone to rupture and therefore require more medical attention.
Wissenschaftlicher Artikel
Scientific Article
Themelis, G. ; Harlaar, N.J. ; Kelder, W.* ; Bart, J.* ; Sarantopoulos, A. ; van, Dam, G.M.* ; Ntziachristos, V.
Ann. Surg. Oncol. 18, 3506-3513 (2011)
BACKGROUND: This study was designed to improve the surgical procedure and outcome of cancer surgery by means of real-time molecular imaging feedback of tumor spread and margin delineation using targeted near-infrared fluorescent probes with specificity to tumor biomarkers. Surgical excision of cancer often is confronted with difficulties in the identification of cancer spread and the accurate delineation of tumor margins. Currently, the assessment of tumor borders is afforded by postoperative pathology or, less reliably, intraoperative frozen sectioning. Fluorescence imaging is a natural modality for intraoperative use by directly relating to the surgeon's vision and offers highly attractive characteristics, such as high-resolution, sensitivity, and portability. Via the use of targeted probes it also becomes highly tumor-specific and can lead to significant improvements in surgical procedures and outcome. METHODS: Mice bearing xenograft human tumors were injected with α(v)β(3)-integrin receptor-targeted fluorescent probe and in vivo visualized by using a novel, real-time, multispectral fluorescence imaging system. Confirmatory ex vivo imaging, bioluminescence imaging, and histopathology were used to validate the in vivo findings. RESULTS: Fluorescence images were all in good correspondence with the confirming bioluminescence images in respect to signal colocalization. Fluorescence imaging detected all tumors and successfully guided total tumor excision by effectively detecting small tumor residuals, which occasionally were missed by the surgeon. Tumor tissue exhibited target-to-background ratio of ~4.0, which was significantly higher compared with white-light images representing the visual contrast. Histopathology confirmed the capability of the method to identify tumor negative margins with high specificity and better prediction rate compared with visual inspection. CONCLUSIONS: Real-time multispectral fluorescence imaging using tumor specific molecular probes is a promising modality for tumor excision by offering real time feedback to the surgeon in the operating room.
Wissenschaftlicher Artikel
Scientific Article
Rosenthal, A. ; Jetzfellner, T. ; Razansky, D. ; Ntziachristos, V.
Proc. SPIE 7899:78992R (2011)
We present a fast inversion algorithm for quantitative two- and three-dimensional optoacoustic tomography. The algorithm is based on an accurate and efficient forward model, which eliminates the need for regularization in the inversion and can achieve real-time performance. The reconstruction speed and other algorithmic performances are demonstrated using numerical simulation studies and experimentally on tissue-mimicking optically heterogeneous phantoms and small animals. In the experimental examples, the model-based reconstructions manifested correctly the effect of light attenuation through the objects and did not suffer from the artifacts which usually afflict the commonly used filtered backprojection algorithms, such as negative absorption values.
Wissenschaftlicher Artikel
Scientific Article
Kellnberger, S. ; Hajiaboli, A. ; Sergiadis, G. ; Razansky, D. ; Ntziachristos, V.
Proc. SPIE 8089:808905 (2011)
Existing imaging modalities like microwave- or radiofrequency (RF) induced thermoacoustic tomography systems show the potential for resolving structures deep inside tissue due to the high penetration properties of RF. However, one of the major drawbacks of existing thermoacoustic tomography systems with pulse modulated carrier frequency excitation is the compromise between efficient signal generation and attainable spatial resolution. In order to overcome limitations of conventional thermoacoustic imaging methods, we herein present and experimentally validate our novel approach towards high resolution thermoacoustic tomography. Instead of carrier-frequency amplification, we utilize ultrahigh-energy electromagnetic impulses at nanosecond duration with near-field energy coupling, thus maintaining thermoacoustic signal strength without compromising spatial resolution. Preliminary experiments on highly absorbing objects, consisting of copper wires with characteristic sizes of ~100 μm, reveal the resolution performance which yields 160 μm. Furthermore, benefits like its cost effectiveness, simplicity and compactness with the potential application in small animal imaging as well as human body imaging show that thermoacoustic tomography with impulse excitation is a promising imaging modality which has a broad range of applications.
Wissenschaftlicher Artikel
Scientific Article
Oancea, A. ; Razansky, D. ; Ntziachristos, V.
Proc. SPIE 8089:808908 (2011)
Optoacoustic imaging can noninvasively provide visualization of vasculature structures with optical contrast well below the skin surface. For meaningful biological investigations, high-resolution at mesoscopic penetration depths and therefore thorough adaption of the systematic arrangement to the object of interest is required. A suitable modular optoacoustic tomography system is presented here and its performance is demonstrated in three exemplary studies on imaging agar phantoms, mouse head vasculature and mouse tumor vasculature ex-vivo.
Wissenschaftlicher Artikel
Scientific Article
Rosenthal, A. ; Razansky, D. ; Ntziachristos, V.
Opt. Lett. 36, 1833-1835 (2011)
A highly sensitive compact hydrophone, based on a pi-phase-shifted fiber Bragg grating, has been developed for the measurement of wideband ultrasonic fields. The grating exhibits a sharp resonance, whose centroid wavelength is pressure sensitive. The resonance is monitored by a continuous-wave (CW) laser to measure ultrasound-induced pressure variations within the grating. In contrast to standard fiber sensors, the high finesse of the resonance-which is the reason for the sensor's high sensitivity-is not associated with a long propagation length. Light localization around the phase shift reduces the effective size of the sensor below that of the grating and is scaled inversely with the resonance spectral width. In our system, an effective sensor length of 270 μm, pressure sensitivity of 440 Pa, and effective bandwidth of 10 MHz were achieved. This performance makes our design attractive for medical imaging applications, such as optoacoustic tomography, in which compact, sensitive, and wideband acoustic detectors are required.
Wissenschaftlicher Artikel
Scientific Article
Pike, L.S.* ; Tannous, B.A.* ; Deliolanis, N.C. ; Hsich, G.* ; Morse, D.* ; Tung, C.H.* ; Sena-Esteves, M.* ; Breakefield, X.O.*
Gene Ther. 18, 1173-1178 (2011)
Adeno-associated virus (AAV)-mediated gene replacement for lysosomal disorders have been spurred by the ability of some serotypes to efficiently transduce neurons in the brain and by the ability of lysosomal enzymes to cross-correct among cells. Here, we explored enzyme replacement therapy in a knock-out mouse model of congenital neuronal ceroid lipofuscinosis (NCL), the most severe of the NCLs in humans. The missing protease in this disorder, cathepsin D (CathD) has high levels in the central nervous system. This enzyme has the potential advantage for assessing experimental therapy in that it can be imaged using a near-infrared fluorescence (NIRF) probe activated by CathD. Injections of an AAV2/rh8 vector-encoding mouse CathD (mCathD) into both cerebral ventricles and peritoneum of newborn knock-out mice resulted in a significant increase in lifespan. Successful delivery of active CathD by the AAV2/rh8-mCathD vector was verified by NIRF imaging of mouse embryonic fibroblasts from knock-out mice in culture, as well as by ex vivo NIRF imaging of the brain and liver after gene transfer. These studies support the potential effectiveness and imaging evaluation of enzyme replacement therapy to the brain and other organs in CathD null mice via AAV-mediated gene delivery in neonatal animals.
Wissenschaftlicher Artikel
Scientific Article
Sarantopoulos, A. ; Themelis, G. ; Ntziachristos, V.
Mol. Imaging Biol. 13, 874-885 (2011)
Purpose: The increasing availability of fluorescent probes for in vivo optical imaging enables the interrogation of complex biological processes in small animals serving as models for human-like tissue function and disease. However, the validation of probe bio-distribution during their development or the study of different disease models, in support of in vivo imaging studies, is not straightforward. Procedures: The imaging system developed consists of a customized multispectral planar imager that has been adapted on a commercial cryomicrotome and provides a powerful modality for ex vivo imaging of small animals. Results: The ability to capture 3D anatomical (color) and fluorescence volumetric distributions of multiple fluorescent markers in high resolution is showcased. Conclusions: Serving both as a method for accurately imaging the bio-distribution of multiple fluorescent agents inside organisms and as a modality for the validation of non-invasive methods, multispectral cryoslicing imaging offers useful insights to ex vivo optical imaging of molecular probes.
Wissenschaftlicher Artikel
Scientific Article
Taruttis, A. ; Herzog, E. ; Razansky, D. ; Ntziachristos, V.
Proc. SPIE 7899:789913 (2011)
Multispectral Optoacoustic Tomography (MSOT) is an emerging technique for high resolution macroscopic imaging with optical and molecular contrast. We present cardiovascular imaging results from a multi-element real-time MSOT system recently developed for studies on small animals. Anatomical features relevant to cardiovascular disease, such as the carotid arteries, the aorta and the heart, are imaged in mice. The system's fast acquisition time, in tens of microseconds, allows images free of motion artifacts from heartbeat and respiration. Additionally, we present in-vivo detection of optical imaging agents, gold nanorods, at high spatial and temporal resolution, paving the way for molecular imaging applications.
Wissenschaftlicher Artikel
Scientific Article
Razansky, D. ; Kellnberger, S. ; Ntziachristos, V.
Proc. SPIE 7899:78993B (2011)
Herein we suggest and experimentally validate a novel thermoacoustic imaging method that relies on near-field exposure of the object to ultrashort impulses of safe radiofrequency energies. The physical rationale behind the Near-field Radiofrequency Tomography (NRT) is the well known ability of biological tissues to absorb a very significant portion of energy when closely coupled to radiofrequency and microwave sources. Compared to existing thermoacoustic imaging implementations, NRT offers a significantly simpler and cost-effective technology that uses high energy impulses instead of expensive and inefficient carrier-frequency amplification methods, making it possible to achieve significantly better imaging resolution without compromising thermoacoustic signal strength.
Wissenschaftlicher Artikel
Scientific Article
Stangl, S. ; Gehrmann, M. ; Dressel, R. ; Alves, F. ; Dullin, C. ; Themelis, G. ; Ntziachristos, V. ; Staeblein, E. ; Walch, A.K. ; Winkelmann, I. ; Multhoff, G.
J. Cell. Mol. Med. 15, 874-887 (2011)
The major stress-inducible heat shock protein 70 (Hsp70) is frequently present on the cell surface of human tumors, but not on normal cells. Herein, the binding characteristics of the cmHsp70.1 mouse monoclonal antibody (mAb) were evaluated in vitro and in a syngeneic tumor mouse model. More than 50% of the CT26 mouse colon carcinoma cells express Hsp70 on their cell surface at 4 degrees C. After a temperature shift to 37 degrees C, the cmHsp70.1-FITC mAb translocates into early endosomes and lysosomes Intraoperative and near-infrared fluorescence (NIRF) imaging revealed an enrichment of Cy5.5-conjugated mAb cmHsp70.1, but not an identically labelled IgG1 isotype-matched control, in i.p. and s.c. located CT26 tumors, as soon as 30min after i.v. injection into the tail vein. Due to the rapid turnover rate of membrane-bound Hsp70, the fluorescence-labelled cmHsp70.1 mAb became endocytosed and accumulated in the tumor, reaching a maximum after 24h and remained detectable at least up to 96h after a single i.v. injection. The tumor-selective internalization of mAb cmHsp70.1 at the physiological temperature of 37 degrees C might enable a targeted uptake of toxins or radionuclides into Hsp70 membrane-positive tumors. The anti-tumoral activity of the cmHsp70.1 mAb is further supported by its capacity to mediate antibody dependent cytotoxicity (ADCC).
Wissenschaftlicher Artikel
Scientific Article
Vinegoni, C.* ; Botnaru, I.* ; Aikawa, E.* ; Calfon, M.A.* ; Iwamoto, Y.* ; Folco, E.J.* ; Ntziachristos, V. ; Weissleder, R.* ; Libby, P.* ; Jaffer, F.A.
Sci. Transl. Med. 3:84ra85 (2011)
New high-resolution molecular and structural imaging strategies are needed to visualize high-risk plaques that are likely to cause acute myocardial infarction, because current diagnostic methods do not reliably identify at-risk subjects. Although molecular imaging agents are available for low-resolution detection of atherosclerosis in large arteries, a lack of imaging agents coupled to high-resolution modalities has limited molecular imaging of atherosclerosis in the smaller coronary arteries. Here, we have demonstrated that indocyanine green (ICG), a Food and Drug Administration-approved near-infrared fluorescence (NIRF)-emitting compound, targets atheromas within 20 min of injection and provides sufficient signal enhancement for in vivo detection of lipid-rich, inflamed, coronary-sized plaques in atherosclerotic rabbits. In vivo NIRF sensing was achieved with an intravascular wire in the aorta, a vessel of comparable caliber to human coronary arteries. Ex vivo fluorescence reflectance imaging showed high plaque target-to-background ratios in atheroma-bearing rabbits injected with ICG compared to atheroma-bearing rabbits injected with saline. In vitro studies using human macrophages established that ICG preferentially targets lipid-loaded macrophages. In an early clinical study of human atheroma specimens from four patients, we found that ICG colocalized with plaque macrophages and lipids. The atheroma-targeting capability of ICG has the potential to accelerate the clinical development of NIRF molecular imaging of high-risk plaques in humans.
Wissenschaftlicher Artikel
Scientific Article
Jetzfellner, T. ; Rosenthal, A. ; Englmeier, K.-H. ; Dima, A. ; Angel Araque Caballero, M. ; Razansky, D. ; Ntziachristos, V.
Appl. Phys. Lett. 98:163701 (2011)
Neuroscience investigations may significantly benefit from the availability of accurate imaging methods of brain parameters in small animals. In this letter, we investigate the imaging performance of the recently introduced interpolated model-matrix inversion (IMMI), in quantitative optoacoustic imaging of the mouse head. We compare the findings of the method against back-projection inversion methods that have more commonly been considered. We find that cross-sectional images of the mouse head accurately match anatomical structures seen on cryosliced head images serving as the gold standard. Moreover, superior imaging performance is found for IMMI compared to previously reported optoacoustic imaging of the mouse head.
Wissenschaftlicher Artikel
Scientific Article
Yoo, H.* ; Kim, J.W.* ; Shishkov, M.* ; Namati, E.* ; Morse, T.* ; Shubochkin, R.* ; McCarthy, J.R.* ; Ntziachristos, V. ; Bouma, B.E.* ; Jaffer, F.A.* ; Tearney, G.J.*
J. Nat. Med. 17, 1680-1684 (2011)
Advancing understanding of human coronary artery disease requires new methods that can be used in patients for studying atherosclerotic plaque microstructure in relation to the molecular mechanisms that underlie its initiation, progression and clinical complications, including myocardial infarction and sudden cardiac death. Here we report a dual-modality intra-arterial catheter for simultaneous microstructural and molecular imaging in vivo using a combination of optical frequency domain imaging (OFDI) and near-infrared fluorescence (NIRF) imaging. By providing simultaneous molecular information in the context of the surrounding tissue microstructure, this new catheter could provide new opportunities for investigating coronary atherosclerosis and stent healing and for identifying high-risk biological and structural coronary arterial plaques in vivo.
Wissenschaftlicher Artikel
Scientific Article
Crane, L.M.A.* ; Themelis, G. ; Pleijhuis, R.G.* ; Harlaar, N.J. ; Sarantopoulos, A. ; Arts, H.J.* ; van der Zee, A.G.J.* ; Vasilis, N. ; van Dam, G.M.*
Mol. Imaging Biol. 13, 1043-1049 (2011)
PURPOSE: Real-time intraoperative near-infrared fluorescence (NIRF) imaging is a promising technique for lymphatic mapping and sentinel lymph node (SLN) detection. The purpose of this technical feasibility pilot study was to evaluate the applicability of NIRF imaging with indocyanin green (ICG) for the detection of the SLN in cervical cancer. PROCEDURES: In ten patients with early stage cervical cancer, a mixture of patent blue and ICG was injected into the cervix uteri during surgery. Real-time color and fluorescence videos and images were acquired using a custom-made multispectral fluorescence camera system. RESULTS: Real-time fluorescence lymphatic mapping was observed in vivo in six patients; a total of nine SLNs were detected, of which one (11%) contained metastases. Ex vivo fluorescence imaging revealed the remaining fluorescent signal in 11 of 197 non-sentinel LNs (5%), of which one contained metastatic tumor tissue. None of the non-fluorescent LNs contained metastases. CONCLUSIONS: We conclude that lymphatic mapping and detection of the SLN in cervical cancer using intraoperative NIRF imaging is technically feasible. However, the technique needs to be refined for full applicability in cervical cancer in terms of sensitivity and specificity.
Wissenschaftlicher Artikel
Scientific Article
Crane, L.M.* ; Themelis, G. ; Arts, H.J.* ; Buddingh, K.T.* ; Brouwers, A.H.* ; Ntziachristos, V. ; van Dam, G.M.* ; van der Zee, A.G.*
Gynecol. Oncol. 120, 291-295 (2011)
OBJECTIVE: Disadvantages of the combined sentinel lymph node (SLN) procedure with radiocolloid and blue dye in vulvar cancer are the preoperative injections of radioactive tracer in the vulva, posing a painful burden on the patient. Intraoperative transcutaneous imaging of a peritumorally injected fluorescent tracer may lead to a one-step procedure, while maintaining high sensitivity. Aim of this pilot study was to investigate the applicability of intraoperative fluorescence imaging for SLN detection and transcutaneous lymphatic mapping in vulvar cancer. METHODS: Ten patients with early stage squamous cell carcinoma of the vulva underwent the standard SLN procedure. Additionally, a mixture of 1mL patent blue and 1mL indocyanin green (ICG; 0.5mg/mL) was injected immediately prior to surgery, with the patient under anesthesia. Color and fluorescence images and videos of lymph flow were acquired using a custom-made intraoperative fluorescence camera system. The distance between skin and femoral artery was determined on preoperative CT-scan as a measure for subcutaneous adipose tissue. RESULTS: In 10 patients, SLNs were detected in 16 groins (4 unilateral; 6 midline tumors). Transcutaneous lymphatic mapping was possible in five patients (5 of 16 groins), and was limited to lean patients, with a maximal distance between femoral artery and skin of 24mm, as determined on CT. In total, 29 SLNs were detected by radiocolloid, of which 26 were also detected by fluorescence and 21 were blue. CONCLUSIONS: These first clinical results indicate that intraoperative transcutaneous lymphatic mapping using fluorescence is technically feasible in a subgroup of lean vulvar cancer patients.
Wissenschaftlicher Artikel
Scientific Article
Terwisscha van Scheltinga, A.G.* ; van Dam, G.M.* ; Nagengast, W.B.* ; Ntziachristos, V. ; Hollema, H.* ; Herek, J.L.* ; Schröder, C.P.* ; Kosterink, J.G.* ; Lub-de, Hoog, M.N.* ; de Vries, E.G.*
J. Nucl. Med. 52, 1778-1785 (2011)
Fluorescence imaging is currently attracting much interest as a method for intraoperative tumor detection, but most current tracers lack tumor specificity. Therefore, this technique can be further improved by tumor-specific detection. With tumor-targeted antibodies bound to a radioactive label, tumor-specific SPECT or PET is feasible in the clinical setting. The aim of the present study was to apply antibody-based tumor detection to intraoperative optical imaging, using preclinical in vivo mouse models. METHODS: Anti-vascular endothelial growth factor (VEGF) antibody bevacizumab and anti-human epidermal growth factor receptor (HER) 2 antibody trastuzumab were labeled with the near-infrared (NIR) fluorescence dye IRDye 800CW. Tumor uptake of the fluorescent tracers and their (89)Zr-labeled radioactive counterparts for PET was determined in human xenograft-bearing athymic mice during 1 wk after tracer injection, followed by ex vivo biodistribution and pathologic examination. Intraoperative imaging of fluorescent VEGF- or HER2-positive tumor lesions was performed in subcutaneous tumors and in intraperitoneal dissemination tumor models. RESULTS: Tumor-to-background ratios, with fluorescent imaging, were 1.93 ± 0.40 for bevacizumab and 2.92 ± 0.29 for trastuzumab on day 6 after tracer injection. Real-time intraoperative imaging detected tumor lesions at even the submillimeter level in intraperitoneal dissemination tumor models. These results were supported by standard histology, immunohistochemistry, and fluorescence microscopy analyses. CONCLUSION: NIR fluorescence-labeled antibodies targeting VEGF or HER2 can be used for highly specific and sensitive detection of tumor lesions in vivo. These preclinical findings encourage future clinical studies with NIR fluorescence-labeled tumor-specific antibodies for intraoperative-guided surgery in cancer patients.
Wissenschaftlicher Artikel
Scientific Article
van Dam, G.M.* ; Themelis, G. ; Crane, L.M.* ; Harlaar, N.J. ; Pleijhuis, R.G.* ; Kelder, W.* ; Sarantopoulos, A. ; de Jong, J.S.* ; Arts, H.J.* ; van der Zee, A.G.* ; Bart, J.* ; Low, P.S.* ; Ntziachristos, V.
J. Nat. Med. 17, 1315-1319 (2011)
The prognosis in advanced-stage ovarian cancer remains poor. Tumor-specific intraoperative fluorescence imaging may improve staging and debulking efforts in cytoreductive surgery and thereby improve prognosis. The overexpression of folate receptor-α (FR-α) in 90-95% of epithelial ovarian cancers prompted the investigation of intraoperative tumor-specific fluorescence imaging in ovarian cancer surgery using an FR-α-targeted fluorescent agent. In patients with ovarian cancer, intraoperative tumor-specific fluorescence imaging with an FR-α-targeted fluorescent agent showcased the potential applications in patients with ovarian cancer for improved intraoperative staging and more radical cytoreductive surgery.
Wissenschaftlicher Artikel
Scientific Article
Sinner, M.F.* ; Lubitz, SA.* ; Pfeufer, A. ; Makino, S.* ; Beckmann, B.M.* ; Lunetta, K.L.* ; Steinbeck, G.* ; Perz, S. ; Rahman, R.* ; Sonni, A.* ; Greenberg, S.M.* ; Furie, K.L.* ; Wichmann, H.-E. ; Meitinger, T. ; Peters, A. ; Benjamin, E.J.* ; Rosand, J.* ; Ellinor, P.T.* ; Kääb, S.*
Heart Rhythm 8, 403-409 (2011)
Atrial fibrillation (AF) is the most common sustained arrhythmia and has a substantial heritable component. Numerous associations between single nucleotide polymorphisms (SNPs) and AF have been described, but few have been replicated. We sought to systematically replicate SNPs that are reported to be associated with AF in two large study samples of European descent. METHODS: We searched PubMed for studies reporting associations between SNPs and AF published before July 1, 2007. SNPs were genotyped in two independent case-control samples from Germany and the United States. Associations between SNPs and AF were assessed using logistic regression models adjusting for age, sex, and hypertension. A meta-analysis of the results from the two studies was performed. RESULTS: We identified 21 SNPs and the angiotensin-converting enzyme insertion/deletion polymorphism that were reported to be associated with AF in the literature. Nine of these genetic variants were not represented on common genome-wide SNP arrays. We successfully genotyped 21 of these 22 variants in 2,145 cases with AF from the German Competence Network for Atrial Fibrillation and 4,073 controls from the KORA S4 study and 16 variants in 790 cases and 1,330 controls from the Massachusetts General Hospital. None of the SNPs replicated in independent populations with AF. CONCLUSION: Our results suggest that previously reported associations to AF were likely false positives and highlight the need for systematic replication of genetic associations in large, independent cohorts to accurately detect variants associated with disease.
Wissenschaftlicher Artikel
Scientific Article
Dean-Ben, X.L. ; Razansky, D. ; Ntziachristos, V.
Proc. SPIE 8090:809017 (2011)
We present in this work a method to estimate the distribution of acoustic scatterers within the imaged sample in an optoacoustic tomographic setup and, subsequently, to reduce the artefacts in the tomographic reconstructions due to reflection or scattering events. The procedure to determine the position of the scatterers consists of measuring the scattered waves generated at a point light absorber located in between the transducer and the imaged sample. Such absorber is positioned in a way that the acoustic waves generated at this absorber and scattered within the sample arrive at the position of the transducer after the waves generated within the sample that propagate directly until the measuring point. Then, the signals captured by the acoustic transducer can be used to reconstruct the distribution of acoustic scatterers and to perform the optoacoustic reconstruction itself. Also, the information retrived on the distribution of acoustic scatterers can be used to improve the optoacoustic tomographic reconstructions. For this, we use a modification of the filtered back-projection algorithm based on weighting the signals with the probability that they are not affected by scattered or reflected waves, so that the artefacts in the images due to these acoustic phenomena are reduced. The experimental results obtained with a tissue-mimicking phantom in which a straw filled with air was included in order to cause scattering of the acoustic waves indicate a good performance of the method proposed.
Wissenschaftlicher Artikel
Scientific Article
Rosenthal, A. ; Ntziachristos, V. ; Razansky, D.
Med. Phys. 38, 4285-4295 (2011)
PURPOSE: Optoacoustic imaging enables mapping the optical absorption of biological tissue using optical excitation and acoustic detection. Although most image-reconstruction algorithms are based on the assumption of a detector with an isotropic sensitivity, the geometry of the detector often leads to a response with spatially dependent magnitude and bandwidth. This effect may lead to attenuation or distortion in the recorded signal and, consequently, in the reconstructed image. METHODS: Herein, an accurate numerical method for simulating the spatially dependent response of an arbitrary-shape acoustic transducer is presented. The method is based on an analytical solution obtained for a two-dimensional line detector. The calculated response is incorporated in the forward model matrix of an optoacoustic imaging setup using temporal convolution, and image reconstruction is performed by inverting the matrix relation. RESULTS: The method was numerically and experimentally demonstrated in two dimensions for both flat and focused transducers and compared to the spatial-convolution method. In forward simulations, the developed method did not suffer from the numerical errors exhibited by the spatial-convolution method. In reconstruction simulations and experiments, the use of both temporal-convolution and spatial-convolution methods lead to an enhancement in resolution compared to a reconstruction with a point detector model. However, because of its higher modeling accuracy, the temporal-convolution method achieved a noise figure approximated three times lower than the spatial-convolution method. CONCLUSIONS: The demonstrated performance of the spatial-convolution method shows it is a powerful tool for reducing reconstruction artifacts originating from the detector finite size and improving the quality of optoacoustic reconstructions. Furthermore, the method may be used for assessing new system designs. Specifically, detectors with nonstandard shapes may be investigated.
Wissenschaftlicher Artikel
Scientific Article
Bühler, A. ; Rosenthal, A. ; Jetzfellner, T. ; Dima, A. ; Razansky, D. ; Ntziachristos, V.
Med. Phys. 38, 1694-1704 (2011)
Purpose: Optoacoustic imaging is an emerging noninvasive imaging modality that can resolve optical contrast through several millimeters to centimeters of tissue with diffraction-limited resolution of ultrasound. Yet, quantified reconstruction of tissue absorption maps requires optoacoustic signals to be collected from as many locations around the object as possible. In many tomographic imaging scenarios, however, only limited-view or partial projection data are available, which has been shown to generate image artifacts and overall loss of quantification accuracy. In this article, the recently introduced interpolated-matrix-model optoacoustic inversion method is tested in different limited-view scenarios and compared to the standard backprojection algorithm. Both direct (TGSVD) and iterative (PLSQR) regularization methods are proposed to improve the accuracy of image reconstructions with their performance tested on simulated and experimental data. While for full-view tomographic data the model-based inversion has been generally shown to attain higher reconstruction accuracy compared to backprojection algorithms, the incomplete tomographic datasets lead to ill-conditioned forward matrices and, consequently, to error-prone inversions, with strong artifacts following a distinct ripple-type pattern. The proposed regularization techniques are shown to stabilize the inversion and eliminate the artifacts. Overall, it has been determined that the regularized interpolated-matrix-model-based optoacoustic inversions show higher accuracy than reconstructions with the standard backprojection algorithm. Finally, the combination of model-based inversion with PLSQR or TGSVD regularization methods can lead to an accurate reconstruction of limited-projection angle optoacoustic data and practical systems for optoacoustic imaging in many realistic cases where the full-view dataset is unavailable.
Wissenschaftlicher Artikel
Scientific Article
Peters, A. ; Döring, A. ; Ladwig, K.-H. ; Meisinger, C. ; Linkohr, B. ; Autenrieth, C. ; Baumeister, S.E.* ; Behr, J.* ; Bergner, A.* ; Bickel, H.* ; Bidlingmaier, M.* ; Dias, A.* ; Emeny, R.T. ; Fischer, B.* ; Grill, E.* ; Gorzelniak, L. ; Hänsch, H. ; Heidbreder, S. ; Heier, M. ; Horsch, A.* ; Huber, D.* ; Huber, R.M.* ; Jörres, R.A.* ; Kääb, S.* ; Karrasch, S.* ; Kirchberger, I. ; Klug, G.* ; Kranz, B.* ; Kuch, B.* ; Lacruz, M.E. ; Lang, O. ; Mielck, A. ; Nowak, D.* ; Perz, S.* ; Schneider, A.E. ; Schulz, S. ; Müller, M.* ; Seidl, H. ; Strobl, R.* ; Thorand, B. ; Wende, R.* ; Weidenhammer, W.* ; Zimmermann, A.-K. ; Wichmann, H.-E. ; Holle, R.
Z. Gerontol. Geriatr. 44, Suppl. 2, 2, 41-54 (2011)
Hintergrund. Das KORA-Age-Verbundprojekt hat zum Ziel, die Determinanten und Folgen von Multimorbidität im Alter zu ermitteln und nach Faktoren des erfolgreichen Alterns in der Allgemeinbevölkerung zu suchen. Material und Methoden. Die KORA-Age-Kohorte besteht aus 9197 Personen, die 1943 oder früher geboren wurden und Teilnehmer der KORA-Kohorte (KORA: Kooperative Gesundheitsforschung in der Region Augsburg) zwischen 1984 und 2001 waren. In der randomisierten Interventionsstudie KORINNA (Koronarinfarktnachbehandlung im Alter) wurde ein von Krankenschwestern durchgeführtes Case-Management-Programm mit 338 Herzinfarktpatienten getestet und gesundheitsökonomisch bewertet. Ergebnisse. In der KORA-Age-Kohorte wurden 2734 Todesfälle registriert, 4565 Personen nahmen an einer schriftlichen Befragung und 4127 Personen an einem Telefoninterview teil (Teilnahme: 76,2% bzw. 68,9%). Zusätzlich wurde eine alters- und geschlechtsstratifizierte Stichprobe von 1079 Personen untersucht (Teilnahme: 53,8%). Schlussfolgerung. Das KORA-Age-Verbundprojekt untersuchte eine große bevölkerungsbezogene Stichprobe älterer Menschen, die Aufschluss über die Verteilung und Determinanten von Multimorbidität und erfolgreichem Altern gibt.
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Scientific Article
Jetzfellner, T. ; Rosenthal, A. ; Bühler, A. ; Englmeier, K.-H. ; Razansky, D. ; Ntziachristos, V.
Opt. Lett. 36, 4176-4178 (2011)
Quantification of biomarkers using multispectral optoacoustic tomography can be challenging due to photon fluence variations with depth and spatially heterogeneous tissue optical properties. Herein we introduce a spectral ratio approach that accounts for photon fluence variations. The performance and imaging improvement achieved with the proposed method is showcased both numerically and experimentally in phantoms and mice.
Wissenschaftlicher Artikel
Scientific Article
Razansky, D. ; Harlaar, N.J. ; Hillebrands, J.-L.* ; Taruttis, A. ; Herzog, E. ; Zeebregts, C.J.* ; van Dam, G.M.* ; Ntziachristos, V.
Proc. SPIE 7899:789905 (2011)
In this work, we show, for the first time to our knowledge, that multispectral optoacoustic tomography (MSOT) can deliver high resolution images of activatable molecular probe's distribution, sensitive to matrix metalloproteinases (MMP), deep within optically scattering human carotid specimen. It is further demonstrated that this method can be used in order to provide accurate maps of vulnerable plaque formations in atherosclerotic disease. Moreover, optoacoustic images can simultaneously show the underlining plaque morphology for accurate localization of MMP activity in three dimensions. This performance directly relates to small animal screening applications and to clinical potential as well.
Wissenschaftlicher Artikel
Scientific Article
Heitmann, A.* ; Huebner, T.* ; Schroeder, R.* ; Perz, S. ; Voss, A.*
Med. Biol. Eng. Comput. 49, 41-50 (2011)
This study has aimed to develop a novel pre-diagnostic tool for primary care screening of heart disease based on multivariate short-term heart rate variability (HRV) analyzed by linear (time and frequency domain) and nonlinear methods (compression entropy (CE), detrended fluctuation analysis (DFA), Poincaré plot analysis, symbolic dynamics) applied to 5-min ECG segments. Firstly, we applied HRV analysis to separate healthy subjects (REF) from heart disease patients (PAT). Then to optimize the results, we subdivided both groups according to gender: REF (♂ = 78, ♀ = 53) versus PAT (♂ = 378, ♀ = 115). Finally, we divided REF and PAT into two age subgroups (30-50 years vs. 51-70 years of age) to consider the influence of age on HRV. Heart disease patients were classified using a scoring system based on cut-off values calculated from all HRV indices obtained from the REF. After combining the optimum indices from all different analyzing methods, sensitivities of more than 72% and a specificity of 100% in all subgroups were revealed. Nonlinear indices proved to be better for discriminating heart disease patients from healthy subjects. Multivariate short-term HRV, analyzed by both linear and nonlinear methods appears to be a suitable pre-diagnostic tool for screening heart disease in primary care settings.
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Scientific Article
Kellnberger, S. ; Hajiaboli, A. ; Razansky, D. ; Ntziachristos, V.
Phys. Med. Biol. 56, 3433-3444 (2011)
Near-field radiofrequency thermoacoustic (NRT) tomography is a new imaging method that was developed to mitigate limitations of conventional thermoacoustic imaging approaches, related to hard compromises between signal strength and spatial resolution. By utilizing ultrahigh-energy electromagnetic impulses at ∼20 ns duration along with improved energy absorption coupling in the near-field, this method can deliver high-resolution images without compromising signal to noise ratio. NRT is a promising modality, offering cost-effectiveness and ease of implementation and it can be conveniently scaled to image small animals and humans. However, several of the performance metrics of the method are not yet documented. In this paper, we characterize the expected imaging performance via numerical simulations based on a finite-integration time-domain (FITD) technique and experiments using tissue mimicking phantoms and different biological samples. Furthermore, we show for the first time whole-body tomographic imaging results from mice, revealing clear anatomical details along with highly dissipative inclusions introduced for control. The best spatial resolution achieved for those experiments was 150 µm.
Wissenschaftlicher Artikel
Scientific Article
Pleijhuis, R.G.* ; Langhout, G.C.* ; Helfrich, W.* ; Themelis, G. ; Sarantopoulos, A. ; Crane, L.M.* ; Harlaar, N.J.* ; de Jong, J.S.* ; Ntziachristos, V. ; van Dam, G.M.*
Eur. J. Surg. Oncol. 37, 32-39 (2011)
Breast-conserving surgery (BCS) results in tumour-positive surgical margins in up to 40% of the patients. Therefore, new imaging techniques are needed that support the surgeon with real-time feedback on tumour location and margin status. In this study, the potential of near-infrared fluorescence (NIRF) imaging in BCS for pre- and intraoperative tumour localization, margin status assessment and detection of residual disease was assessed in tissue-simulating breast phantoms.Breast-shaped phantoms were produced with optical properties that closely match those of normal breast tissue. Fluorescent tumour-like inclusions containing indocyanine green (ICG) were positioned at predefined locations in the phantoms to allow for simulation of (i) preoperative tumour localization, (ii) real-time NIRF-guided tumour resection, and (iii) intraoperative margin assessment. Optical imaging was performed using a custom-made clinical prototype NIRF intraoperative camera.Tumour-like inclusions in breast phantoms could be detected up to a depth of 21 mm using a NIRF intraoperative camera system. Real-time NIRF-guided resection of tumour-like inclusions proved feasible. Moreover, intraoperative NIRF imaging reliably detected residual disease in case of inadequate resection.We evaluated the potential of NIRF imaging applications for BCS. The clinical setting was simulated by exploiting tissue-like breast phantoms with fluorescent tumour-like agarose inclusions. From this evaluation, we conclude that intraoperative NIRF imaging is feasible and may improve BCS by providing the surgeon with imaging information on tumour location, margin status, and presence of residual disease in real-time. Clinical studies are needed to further validate these results.
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Scientific Article
Bézière, N. ; Ntziachristos, V.
Gastroenterology 141, 1979-1985 (2011)
no Abstract
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Rosenthal, A. ; Ntziachristos, V. ; Razansky, D.
IEEE Trans. Ultrason. Ferroelectr. Freq. Control. 58, 316-326 (2011)
The frequency response of ultrasonic detectors is commonly calibrated by finding their sensitivity to incident plane waves at discrete frequencies. For certain applications, such as the emerging field of optoacoustic tomography, it is the response to point sources emitting broadband spectra that needs to be found instead. Although these two distinct sensitivity characteristics are interchangeable in the case of a flat detector and a point source at infinity, it is not the case for detectors with size considerably larger than the acoustic wavelength of interest or those having a focused aperture. Such geometries, which are common in optoacoustics, require direct calibration of the acoustic detector using a point source placed in the relevant position. In this paper, we report on novel cross-validating optoacoustic methods for measuring the frequency response of wideband acoustic sensors. The approach developed does not require pre-calibrated hydrophones and therefore can be readily adopted in any existing optoacoustic measurement configuration. The methods are successfully confirmed experimentally by measuring the frequency response of a common piezoelectric detector having a cylindrically focused shape.
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Jetzfellner, T. ; Ntziachristos, V.
J. Innov. Opt. Health Sci. 4, 385-393 (2011)
In this paper, we consider the use of blind deconvolution for optoacoustic (photoacoustic) imaging and investigate the performance of the method as means for increasing the resolution of the reconstructed image beyond the physical restrictions of the system. The method is demonstrated with optoacoustic measurement obtained from six-day-old mice, imaged in the near-infrared using a broadband hydrophone in a circular scanning configuration. We find that estimates of the unknown point spread function, achieved by blind deconvolution, improve the resolution and contrast in the images and show promise for enhancing optoacoustic images.
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Mallas, G.* ; Rosenthal, A. ; Calfon, M.A.* ; Razansky, R.N. ; Mauskapf, A.* ; Jaffer, F.A.* ; Brooks, D.H.* ; Ntziachristos, V.
In: Proceedings (33rd Annual International Conference of the IEEE EMBS, 30th August - 3rd September 2011, Boston, USA). Piscataway, NJ: IEEE, 2011. 1117-1120
The use of intravascular imaging modalities for the detection and assessment of atherosclerotic plaque is becoming increasingly useful. Current clinical invasive modalities assess the presence of plaque using anatomical information and include Intravascular Ultrasound (IVUS) and Optical Coherence Tomography (OCT). However, such modalities cannot take into account underlying functional biological information, which can however be revealed with the use of molecular imaging. Consequently, intravascular molecular imaging is emerging as a powerful approach. We have developed such a Near-Infrared Fluorescence (NIRF) imaging system and showcased, in both phantom and in-vivo (rabbit) experiments, its potential to successfully detect inflamed atherosclerotic plaques, using appropriate fluorescent probes. Here, we discuss some limitations of the current system and suggest the combined use of the NIRF and IVUS imaging systems as a means for more accurate assessment of atherosclerotic plaque. We include some results and models that showcase the potential power of this kind of hybrid imaging.
Busch, A.* ; Claßen, K.* ; Groß, A.* ; Gaden, U.* ; Häring, S.* ; Heusinger, S.* ; Hildebrand, C. ; Klein, B.* ; Klippert, J.* ; Loss, K.* ; Metzger, N.* ; Ott, A.* ; Schindler, B.* ; Scholtysek, F.* ; Schöpe, L.* ; Seitz, T.* ; Sträter, O.* ; Villela, K.*
Berlin: VDE-Verl., 2011. 124 S. (Produkte, Dienstleistungen, Systeme ; 6/2011)
Die demografische Entwicklung in Europa geht mit dem Wunsch eines gesunden und unabhängigen Lebens bis ins hohe Alter einher. Dies kann durch entsprechende altersgerechte Assistenzsysteme erreicht werden, welche die Interaktion zwischen technischen und sozialen Systemen verbessern. Im Rahmen der Förderinitiative „Altersgerechte Assistenzsysteme für ein gesundes und unabhängiges Leben – AAL“ des BMBF wird der Entwicklung entsprechender Assistenzsysteme Rechnung getragen. Die Arbeitsgruppe Qualitätskriterien hat sich zum Ziel gesetzt, dieses gemeinsame Verständnis zu fördern. Hierzu hat die Arbeitsgruppe das vorliegende Whitepaper aufgestellt. Es dient dem direkten Anwender und den privaten sowie öffentlichen Dienstleistern von AAL-Produkten zur Orientierung bei relevanten Qualitätskriterien für den Aufbau einer AAL-Umgebung. Hersteller und Kostenträger erfahren, welche Qualitätskriterien im besonderen Umfeld von AAL von Bedeutung sind.
Björn, S. ; Englmeier, K.-H. ; Ntziachristos, V. ; Schulz, R.B.
J. Biomed. Opt. 16:046005 (2011)
Mesoscopic epifluorescence tomography is a novel technique that discovers fluorescence bio-distribution in small animals by tomographic means in reflectance geometry. A collimated laser beam is scanned over the skin surface to excite fluorophores hidden within the tissue while a CCD camera acquires an image of the fluorescence emission for each source position. This configuration is highly efficient in the visible spectrum range where trans-illumination imaging of small animals is not feasible due to the high tissue absorption and scattering in biological organisms. The reconstruction algorithm is similar to the one used in fluorescence molecular tomography. However, diffusion theory cannot be employed since the source-detector separation for most image pixels is comparable to or below the scattering length of the tissue. Instead Monte Carlo simulations are utilized to predict the sensitivity functions. In a phantom study we show the effect of using enhanced source grid arrangements during the data acquisition and the reconstruction process to minimize boundary artefacts. Furthermore, we present ex vivo data that show high spatial resolution and quantitative accuracy in heterogeneous tissues using GFP-like fluorescence in B6-albino mice up to a depth of 1100 μm.
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Pyka, T. ; Schulz, R.B. ; Ale, A.B.F. ; Ntziachristos, V.
Opt. Lett. 36, 4329-4331 (2011)
The normalized Born approximation has been suggested as a ratiometric method in fluorescence molecular tomography (FMT) applications, to account for heterogeneity variations. The method enabled practical inversions, as it offered fluorescence reconstruction accuracy over a wide range of absorption heterogeneity, while also accounting for unknown experimental factors, such as the various system gains and losses. Yet it was noted that scattering variations affect the robustness and accuracy. Herein we decompose the effects of absorption and scattering and capitalize on the recent development of hybrid FMT/x-ray computed tomography imaging methods to proposed amendments to the method, which improve the overall accuracy of the approach.
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Rosenthal, A. ; Ntziachristos, V. ; Razansky, D.
Proc. SPIE 7899:78992S (2011)
One of the major challenges of optoacoustic imaging is that it involves relatively weak acoustic signals, which need to be detected with high signal-to-noise ratio (SNR). Because the SNR is generally proportional to the area of the detector's face, large detectors are commonly used. Although the use of such detectors improves the SNR, it may lead to significant signal distortion resulting in artifacts in the reconstructed optoacoustic image. In this work we developed a method for simulating the spatially dependent frequency response of acoustic detectors with arbitrary surface shapes. The frequency response is incorporated into a forward model for optoacoustic propagation. Our method can be used for designing detectors with desired properties and reducing reconstruction artifacts caused by the response of finite-size detectors.
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Morscher, S. ; Glatz, J. ; Deliolanis, N.C. ; Bühler, A. ; Sarantopoulos, A. ; Razansky, D. ; Ntziachristos, V.
Proc. SPIE 8089:80890R (2011)
In this work, we show, for the first time to our knowledge, that multispectral optoacoustic tomography (MSOT) can deliver high resolution images of activatable molecular probe's distribution, sensitive to matrix metalloproteinases (MMP), deep within optically scattering human carotid specimen. It is further demonstrated that this method can be used in order to provide accurate maps of vulnerable plaque formations in atherosclerotic disease. Moreover, optoacoustic images can simultaneously show the underlining plaque morphology for accurate localization of MMP activity in three dimensions. This performance directly relates to small animal screening applications and to clinical potential as well.
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Dean-Ben, X.L. ; Ma, R. ; Razansky, D. ; Ntziachristos, V.
IEEE Trans. Med. Imaging 30, 401-408 (2011)
A method is presented to reduce artefacts produced in optoacoustic tomography images due to internal reflection or scattering of the acoustic waves. It is based on weighting the tomographic contribution of each detector with the probability that a signal affected by acoustic mismatches is measured at that position. The correction method does not require a priori knowledge of the acoustic or optical properties of the imaged sample. Performance tests were made with agar phantoms that included air gaps for mimicking strong acoustic reflections as well as with an acoustically heterogeneous adult Zebrafish. The results obtained with the method proposed show a clear reduction of the artefacts with respect to the original images reconstructed with filtered back-projection algorithm. This performance is directly related to in-vivo small animal imaging applications involving imaging in the presence of bones, lungs, and other highly mismatched organs.
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Dean-Ben, X.L. ; Ntziachristos, V. ; Razansky, D.
Appl. Phys. Lett. 98:171110 (2011)
Strong reflection and scattering effects, arising at the boundaries of acoustically mismatched areas in living organisms, such as bones, lungs, and other air cavities, may introduce severe image artifacts into optoacoustic reconstructions. Yet, in many cases, an a priori knowledge on the location of strongly mismatched areas is available, either based on general anatomical knowledge or using other imaging modalities. In this letter, we suggest a statistical optoacoustic image reconstruction method, which uses a priori knowledge on the location of acoustic distortions in order to improve image quality and quantification. Significant improvements are showcased experimentally on tissue mimicking phantoms of different complexities.
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Dean-Ben, X.L. ; Razansky, D. ; Ntziachristos, V.
Proc. SPIE 7899:789930 (2011)
A modified quantitative inversion algorithm is presented that minimizes the effects of internal acoustic reflections or scattering in tomographic optoacoustic images. The inversion procedure in our model-based algorithm consists in solving a linear system of equations in which each individual equation corresponds to a given position of the acoustic transducer and to a given time instant. Thus, the modification that we propose in this work consists in weighting each equation of the linear system with the probability that the measured wave is not distorted by reflection or scattering phenomena. We show that the probability that a reflected or scattered wave is detected at a given position and at a given instant is approximately proportional to the size of the area in which the original wave could have been generated, which is dependent on the position of the transducer and on the time instant, so that such probability can be used to weight each equation of the linear system. Thereby, the contribution of the waves that propagate directly to the transducer to the reconstructed images is emphasized. We experimentally test the proposed inversion algorithm with tissue-mimicking agar phantoms in which air-gaps are included to cause reflections of the acoustic waves. The tomographic reconstructions obtained with the modification proposed herein show a clear reduction of the artefacts due to these acoustic phenomena with respect to the reconstructions yielded with the original algorithm. This performance is directly related to in-vivo small animal imaging applications involving imaging in the presence of bones, lungs, and other highly mismatched organs.
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Dean-Ben, X.L. ; Razansky, D. ; Ntziachristos, V.
Phys. Med. Biol. 56, 6129-6148 (2011)
In this paper, it is demonstrated that the effects of acoustic attenuation may play a significant role in establishing the quality of tomographic optoacoustic reconstructions. Accordingly, spatially dependent reduction of signal amplitude leads to quantification errors in the reconstructed distribution of the optical absorption coefficient while signal broadening causes loss of image resolution. Here we propose a correction algorithm for accounting for attenuation effects, which is applicable in both the time and frequency domains. It is further investigated which part of the optoacoustic signal spectrum is practically affected by those effects in realistic imaging scenarios. The validity and benefits of the suggested modelling and correction approaches are experimentally validated in phantom measurements.
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Dean-Ben, X.L. ; Ntziachristos, V. ; Razansky, D.
Proc. SPIE 8090:809013 (2011)
An analysis of the time-shifting correction in optoacoustic tomographic reconstructions for media with an a priori known speed of sound distribution is presented. We describe a modification of the filtered back-projection algorithm, for which the absorbed optical energy at a given point is estimated from the value of the measured signals at the instant corresponding to the time-of-flight between such point and the measuring points. In the case that a non-uniform speed of sound distribution does exist, we estimate the time-of-flight with the straight acoustic rays model, for which acoustic waves are assumed not to change direction as they propagate. The validity of this model is analysed for small speed of sound variations by comparing the predicted values of the time-of-flight with the ones estimated considering the refraction of the waves. Experimental results with tissue-mimicking agar phantoms with a higher speed of sound than water showcase the effects of the time-shifting of the optoacoustic signals caused by the acoustic mismatch. The performance of the time-shifting correction relates to the optoacoustic imaging of biological tissues, for which the speed of sound variations are usually lower than 10%.
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Jetzfellner, T. ; Rosenthal, A. ; Bühler, A. ; Dima, A. ; Englmeier, K.-H. ; Ntziachristos, V. ; Razansky, D.
Proc. SPIE 7899:78991Y (2011)
Obtaining quantified optoacoustic reconstructions is an important and longstanding challenge, mainly caused by the complex heterogeneous structure of biological tissues as well as the lack of accurate and robust reconstruction algorithms. The recently introduced model-based inversion approaches were shown to eliminate some of reconstruction artifacts associated with the commonly used back-projection schemes, while providing an excellent platform for obtaining quantified maps of optical energy deposition in experimental configurations of various complexity. In this work, we introduce a weighted model-based approach, capable of overcoming reconstruction challenges caused by perprojection variations of object's illumination and other partial illumination effects. The universal weighting procedure is equally shown to reduce reconstruction artifacts associated with other experimental imperfections, such as non-uniform transducer sensitivity fields. Significant improvements in image fidelity and quantification are showcased both numerically and experimentally on tissue phantoms.
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Jaffer, F.A.* ; Calfon, M.A.* ; Rosenthal, A. ; Mallas, G.* ; Razansky, R.N. ; Mauskapf, A.* ; Weissleder, R.* ; Libby, P.* ; Ntziachristos, V.
J. Am. Coll. Cardiol. 57, 2516-2526 (2011)
OBJECTIVES: This study sought to develop a 2-dimensional (2D) intravascular near-infrared fluorescence (NIRF) imaging strategy for investigation of arterial inflammation in coronary-sized vessels.BACKGROUND: Molecular imaging of arterial inflammation could provide new insights into the pathogenesis of acute myocardial infarction stemming from coronary atheromata and implanted stents. Presently, few high-resolution approaches can image inflammation in coronary-sized arteries in vivo.METHODS:A new 2.9-F rotational, automated pullback 2D imaging catheter was engineered and optimized for 360° viewing intravascular NIRF imaging. In conjunction with the cysteine protease-activatable imaging reporter Prosense VM110 (VisEn Medical, Woburn, Massachusetts), intra-arterial 2D NIRF imaging was performed in rabbit aortas with atherosclerosis (n =10) or implanted coronary bare-metal stents (n = 10, 3.5-mm diameter, day 7 post-implantation). Intravascular ultrasound provided coregistered anatomical images of arteries. After sacrifice, specimens underwent ex vivo NIRF imaging, fluorescence microscopy, and histological and immunohistochemical analyses. RESULTS: Imaging of coronary artery-scaled phantoms demonstrated 8-sector angular resolution and submillimeter axial resolution, nanomolar sensitivity to NIR fluorochromes, and modest NIRF light attenuation through blood. High-resolution NIRF images of vessel wall inflammation with signal-to-noise ratios >10 were obtained in real-time through blood, without flushing or occlusion. In atherosclerosis, 2D NIRF, intravascular ultrasound-NIRF fusion, microscopy, and immunoblotting studies provided insight into the spatial distribution of plaque protease activity. In stent-implanted vessels, real-time imaging illuminated an edge-based pattern of stent-induced arterial inflammation. CONCLUSIONS: A new 2D intravascular NIRF imaging strategy provides high-resolution in vivo spatial mapping of arterial inflammation in coronary-sized arteries and reveals increased inflammation-regulated cysteine protease activity in atheromata and stent-induced arterial injury.
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Bühler, A. ; Herzog, E. ; Razansky, D. ; Ntziachristos, V.
Proc. SPIE 7899:789914 (2011)
Optoacoustic tomography can visualize optical contrast in tissues while capitalizing on the advantages of ultrasound, such as high spatial resolution and fast imaging capabilities. We report herein on a novel multi-spectral optoacoustic tomography system capable of resolving dynamic contrast at video rate and showcase its performance by monitoring kidney perfusion after injection of Indocyaningreen (ICG).
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Razansky, D. ; Bühler, A. ; Ntziachristos, V.
Nat. Protoc. 6, 1121-1129 (2011)
Multispectral optoacoustic tomography (MSOT) has recently been developed to enable visualization of optical contrast and tissue biomarkers, with resolution and speed representative of ultrasound. In the implementation described here, MSOT enables operation in real-time mode by capturing single cross-sectional images in <1 ms from living small animals (e.g., mice) and other tissues of similar dimensions. At the core of the method is illumination of the object using multiple wavelengths in order to resolve spectrally distinct biomarkers over background tissue chromophores. The system allows horizontal placement of a mouse in the imaging chamber and three-dimensional scanning of the entire body without the need to immerse the mouse in water. Here we provide a detailed description of the MSOT scanner components, system calibration, selection of image reconstruction algorithms and animal handling. Overall, the entire protocol can be completed within 15-30 min for acquisition of a whole-body multispectral data set from a living mouse.
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