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| 2017/03/10 17:22 |
Article of Mafalda Correia on in vivo 4D ultrafast ultrasound flow imaging featured in the Physics in Medicine and Biology Highlights of 2016
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Full-field optical coherence tomography as a diagnosis tool: Recent progress with multimodal imaging.
Thouvenin, O., C. Apelian, A. Nahas, M. Fink, and C. Boccara.
Applied Sciences (Switzerland) 7, no. 3 (2017).
Résumé: © 2017 by the authors.Full-field optical coherence tomography (FF-OCT) is a variant of OCT that is able to register 2D en face views of scattering samples at a given depth. Thanks to its superior resolution, it can quickly reveal information similar to histology without the need to physically section the sample. Sensitivity and specificity levels of diagnosis performed with FF-OCT are 80% to 95% of the equivalent histological diagnosis performances and could therefore benefit from improvement. Therefore, multimodal systems have been designed to increase the diagnostic performance of FF-OCT. In this paper, we will discuss which contrasts can be measured with such multimodal systems in the context of ex vivo biological tissue examination. We will particularly emphasize three multimodal combinations to measure the tissue mechanics, dynamics, and molecular content respectively.
Mots-Clés: Biomechanics; Cellular metabolism; Dynamics; Fluorescence microscopy; Full-field optical coherence tomography; Mechanical properties; Multimodality
Temperature of a nanoparticle above a substrate under radiative heating and cooling.
Kallel, H., R. Carminati, and K. Joulain.
Physical Review B – Condensed Matter and Materials Physics 95, no. 11 (2017).
Résumé: © 2017 American Physical Society.Controlling the temperature in architectures involving nanoparticles and substrates is a key issue for applications involving micro- and nanoscale heat transfer. We study the thermal behavior of a single nanoparticle interacting with a flat substrate under external monochromatic illumination, and with thermal radiation as the unique heat loss channel. We develop a model to compute the temperature of the nanoparticle, based on an effective dipole-polarizability approach. Using numerical simulations, we thoroughly investigate the impacts of various parameters affecting the nanoparticle temperature, such as the nanoparticle-to-substrate gap distance, the incident light wavelength and polarization, or the material resonances. This study provides a tool for the thermal characterization and design of micro- or nanoscale systems coupling substrates with nanoparticles or optical antennas.
Photoacoustic imaging beyond the acoustic diffraction-limit with dynamic speckle illumination and sparse joint support recovery.
Hojman, E., T. Chaigne, O. Solomon, S. Gigan, E. Bossy, Y. C. Eldar, and O. Katz.
Optics Express 25, no. 5 (2017): 4875–4886.
Résumé: © 2017 Optical Society of America.In deep tissue photoacoustic imaging the spatial resolution is inherently limited by the acoustic wavelength. Recently, it was demonstrated that it is possible to surpass the acoustic diffraction limit by analyzing fluctuations in a set of photoacoustic images obtained under unknown speckle illumination patterns. Here, we purpose an approach to boost reconstruction fidelity and resolution, while reducing the number of acquired images by utilizing a compressed sensing computational reconstruction framework. The approach takes into account prior knowledge of the system response and sparsity of the target structure. We provide proof of principle experiments of the approach and demonstrate that improved performance is obtained when both speckle fluctuations and object priors are used. We numerically study the expected performance as a function of the measurement's signal to noise ratio and sample spatial-sparsity. The presented reconstruction framework can be applied to analyze existing photoacoustic experimental data sets containing dynamic fluctuations.
Feasibility of Imaging and Treatment Monitoring of Breast Lesions with Three-Dimensional Shear Wave Elastography.
Athanasiou, A., H. Latorre-Ossa, A. Criton, A. Tardivon, J. L. Gennisson, and M. Tanter.
Ultraschall in der Medizin 38, no. 1 (2017): 51–59.
Résumé: © Georg Thieme Verlag KG Stuttgart · New York.Purpose, Firstly to evaluate the feasibility and diagnostic performance of three-dimensional (3D) shear wave elastography (SWE) volume measurements in patients with breast lesions compared to breast dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) lesion volumes and 3D-US B-mode volumes. Secondly to assess the treatment monitoring performance of 3D-SWE in patients under neoadjuvant chemotherapy for breast cancer by comparing it to 3D-US lesion volume. Materials and Methods, This prospective study was approved by the institutional review board. Informed consent was provided. 33 patients with 33 lesions were included. The feasibility of 3D-SWE was evaluated in 23 patients. In the 10 remaining patients receiving neoadjuvant chemotherapy, 3D-SWE was evaluated before and during treatment. Tumor volume and qualitative and quantitative elasticity analysis measurements were performed and compared to the tumor volume as estimated by 3D-US and DCE-MRI. Statistical analysis was performed using the Pearson correlation coefficient. Results, 3D-SWE was feasible in patients with breast lesions. Tumor volume calculated with 3D-US and 3D-SWE showed very good and moderate concordances with DCE-MRI volume, respectively (Pearson correlation coefficients equal to ρ=r=0.88, p<0.00002 and ρ=r=0.5, p=0.32, respectively). Modification of tumor elasticity and heterogeneity was correlated with response to treatment. In good responders, elasticity and elasticity heterogeneity diminished. Conclusion, Tumor 3D-US volume measurements showed very good concordance with DCE-MRI volume. 3D-SWE can provide valuable information: reduction of tissue stiffness during treatment could be a potential indicator of response. These preliminary results should be confirmed on a larger number of patients.
Mots-Clés: 3D ultrasound; breast; neoadjuvant chemotherapy; tumor