Source: https://www.institut-langevin.espci.fr/journal_articles_2015?lang=fr
Timestamp: 2019-04-20 06:12:06+00:00

Document:
In vivo discrimination of tumor modifications during antiangiogenic and cytotoxic therapy using ultrasonography modalities: Shear Wave Elastography (SWE), Contrast Enhanced Ultrasound (CEUS) and Quantitative Ultrasound (QUS).
Dizeux, A., T. Payen, G. Barrois, M. Lamuraglia, C. Baldini, D. Le Guillou, E. Comperat, J. - L. Gennisson, M. Tanter, M. Oelze et al.
EFSUMB Guidelines on Interventional Ultrasound (INVUS), Part II Diagnostic Ultrasound-Guided Interventional Procedures (Short Version).
Sidhu, P. S., K. Brabrand, V. Cantisani, J. M. Correas, X. W. Cui, M. D'onofrio, M. Essig, S. Freeman, O. H. Gilja, N. Gritzmann et al.
Ultraschall In Der Medizin 36, no. 6 (2015): 566–580.
EFSUMB Guidelines on Interventional Ultrasound (INVUS), Part II Diagnostic Ultrasound-Guided Interventional Procedures (Long Version).
Ultraschall In Der Medizin 36, no. 6 (2015): E15–E35.
Directional source of water waves by a crystal of surface-piercing cylinders.
Chekroun, M., A. Maurel, V. Pagneux, and P. Petitjeans.
Comptes Rendus Mecanique 343, no. 12 (2015): 689–699.
Effective birefringence to analyze sound transmission through a layer with subwavelength slits.
Maurel, A., S. Felix, J. - F. Mercier, and A. Ourir.
Comptes Rendus Mecanique 343, no. 12 (2015): 612–621.
Validation of an intracardiac ultrasonic therapy-imaging dual mode transducer.
Kwiecinski, W., J. Provost, R. Dubois, F. Sacher, M. Haissaguerre, M. Legros, A. Nguyen-Dinh, R. Dufait, M. Tanter, and M. Pernot.
Irbm 36, no. 6 (2015): 351–354.
Competition and Coexistence of Raman and Random Lasing in Silica-/Titania-Based Solid Foams.
Gaikwad, P., N. Bachelard, P. Sebbah, R. Backov, and R. A. L. Vallee.
Advanced Optical Materials 3, no. 11 (2015): 1640–1651.
Plasmonic lateral forces on chiral spheres.
Canaguier-Durand, A., and C. Genet.
Journal of Optics (United Kingdom) 18, no. 1 (2015).
Résumé: © 2016 IOP Publishing Ltd. We show that the optical force exerted on a finite size chiral sphere by a surface plasmon mode has a component along a direction perpendicular to the plasmon linear momentum. We reveal how this chiral lateral force, pointing in opposite directions for opposite enantiomers, stems from an angular-to-linear crossed momentum transfer involving the plasmon transverse spin angular momentum density and mediated by the chirality of the sphere. Our multipolar approach allows us discussing the inclusion of the recoil term in the force on a small sphere taken in the dipolar limit and observing sign inversions of the lateral chiral force when the size of the sphere increases.
Towards new applications using capillary waveguides.
Stasio, N., A. Shibukawa, I. N. Papadopoulos, S. Farahi, O. Simandoux, J. - P. Huignard, E. Bossy, C. Moser, and D. Psaltis.
Biomedical Optics Express 6, no. 23 (2015): 4619–4631.
Fingerprint imaging from the inside of a finger with full-field optical coherence tomography.
Auksorius, E., and A. C. Boccara.
Biomedical Optics Express 6, no. 11 (2015): 4465–4471.
Single molecule study of non-specific binding kinetics of LacI in mammalian cells.
Caccianini, L., D. Normanno, I. Izeddin, and M. Dahan.
Faraday Discussions 184 (2015): 393–400.
Résumé: © The Royal Society of Chemistry. Many key cellular processes are controlled by the association of DNA-binding proteins (DBPs) to specific sites. The kinetics of the search process leading to the binding of DBPs to their target locus are largely determined by transient interactions with non-cognate DNA. Using single-molecule microscopy, we studied the dynamics and non-specific binding to DNA of the Lac repressor (LacI) in the environment of mammalian nuclei. We measured the distribution of the LacI-DNA binding times at non-cognate sites and determined the mean residence time to be τ1D = 182 ms. This non-specific interaction time, measured in the context of an exogenous system such as that of human U2OS cells, is remarkably different compared to that reported for the LacI in its native environment in E. coli (<5 ms). Such a striking difference (more than 30 fold) suggests that the genome, its organization, and the nuclear environment of mammalian cells play important roles on the dynamics of DBPs and their non-specific DNA interactions. Furthermore, we found that the distribution of off-target binding times follows a power law, similar to what was reported for TetR in U2OS cells. We argue that a possible molecular origin of such a power law distribution of residence times is the large variability of non-cognate sequences found in the mammalian nucleus by the diffusing DBPs.
Broadband Coherent Enhancement of Transmission and Absorption in Disordered Media.
Hsu, C. W., A. Goetschy, Y. Bromberg, A. D. Stone, and H. Cao.
Résumé: © 2015 American Physical Society. Spatial modulation of the incident wave front has become a powerful method for controlling the diffusive transport of light in disordered media; however, such interference-based control is intrinsically sensitive to frequency detuning. Here, we show analytically and numerically that certain wave fronts can exhibit strongly enhanced total transmission or absorption across bandwidths that are orders of magnitude broader than the spectral correlation width of the speckles. Such broadband enhancement is possible due to long-range correlations in coherent diffusion, which cause the spectral degrees of freedom to scale as the square root of the bandwidth rather than the bandwidth itself.
Quantitative Shear-Wave Elastography of the Liver in Preterm Neonates with Intra-Uterine Growth Restriction.
Alison, M., V. Biran, A. Tanase, M. Bendavid, M. Blouet, C. Demene, G. Sebag, M. Tanter, and O. Baud.
Plos One 10, no. 11 (2015).
Ultrafast ultrasound localization microscopy for deep super-resolution vascular imaging.
Errico, C., J. Pierre, S. Pezet, Y. Desailly, Z. Lenkei, O. Couture, and M. Tanter.
Nature 527, no. 7579 (2015): 499–502.
Résumé: © 2015 Macmillan Publishers Limited. All rights reserved. Non-invasive imaging deep into organs at microscopic scales remains an open quest in biomedical imaging. Although optical microscopy is still limited to surface imaging owing to optical wave diffusion and fast decorrelation in tissue, revolutionary approaches such as fluorescence photo-activated localization microscopy led to a striking increase in resolution by more than an order of magnitude in the last decade. In contrast with optics, ultrasonic waves propagate deep into organs without losing their coherence and are much less affected by in vivo decorrelation processes. However, their resolution is impeded by the fundamental limits of diffraction, which impose a long-standing trade-off between resolution and penetration. This limits clinical and preclinical ultrasound imaging to a sub-millimetre scale. Here we demonstrate in vivo that ultrasound imaging at ultrafast frame rates (more than 500 frames per second) provides an analogue to optical localization microscopy by capturing the transient signal decorrelation of contrast agents – inert gas microbubbles. Ultrafast ultrasound localization microscopy allowed both non-invasive sub-wavelength structural imaging and haemodynamic quantification of rodent cerebral microvessels (less than ten micrometres in diameter) more than ten millimetres below the tissue surface, leading to transcranial whole-brain imaging within short acquisition times (tens of seconds). After intravenous injection, single echoes from individual microbubbles were detected through ultrafast imaging. Their localization, not limited by diffraction, was accumulated over 75,000 images, yielding 1,000,000 events per coronal plane and statistically independent pixels of ten micrometres in size. Precise temporal tracking of microbubble positions allowed us to extract accurately in-plane velocities of the blood flow with a large dynamic range (from one millimetre per second to several centimetres per second). These results pave the way for deep non-invasive microscopy in animals and humans using ultrasound. We anticipate that ultrafast ultrasound localization microscopy may become an invaluable tool for the fundamental understanding and diagnostics of various disease processes that modify the microvascular blood flow, such as cancer, stroke and arteriosclerosis.
Lagubeau, G., P. Cobelli, T. Bobinski, A. Maurel, V. Pagneux, and P. Petitjeans.
Applied Optics 54, no. 32 (2015): 9409–9414.
High numerical aperture holographic microscopy reconstruction with extended z range.
Verrier, N., D. Donnarumma, G. Tessier, and M. Gross.
Applied Optics 54, no. 32 (2015): 9540–9547.
Spatiotemporal Clutter Filtering of Ultrafast Ultrasound Data Highly Increases Doppler and fUltrasound Sensitivity.
Demene, C., T. Deffieux, M. Pernot, B. - F. Osmanski, V. Biran, J. - L. Gennisson, L. - A. Sieu, A. Bergel, S. Franqui, J. - M. Correas et al.
Ieee Transactions On Medical Imaging 34, no. 11 (2015): 2271–2285.
Nonlinear multiple scattering of acoustic waves by a layer of bubbles.
Lombard, O., C. Barrière, and V. Leroy.
EPL 112, no. 2 (2015).
Résumé: © EPLA, 2015. We present a theoretical and experimental study of the acoustic second-harmonic generation by a single layer of bubbles. This simple system allows us to investigate the subtle interplay between nonlinear effects and multiple scattering. A perturbative model is shown to give an excellent agreement with the experimental measurements, and we demonstrate the existence of an optimal concentration of bubbles, for which the harmonic generation is maximum. The potential of bubble screens as efficient subwavelength acoustic nonlinear sources is discussed.
Resolution limits of ultrafast ultrasound localization microscopy.
Desailly, Y., J. Pierre, O. Couture, and M. Tanter.
Physics in Medicine and Biology 60, no. 22 (2015): 8723–8740.
Résumé: © 2015 Institute of Physics and Engineering in Medicine. As in other imaging methods based on waves, the resolution of ultrasound imaging is limited by the wavelength. However, the diffraction-limit can be overcome by super-localizing single events from isolated sources. In recent years, we developed plane-wave ultrasound allowing frame rates up to 20 000 fps. Ultrafast processes such as rapid movement or disruption of ultrasound contrast agents (UCA) can thus be monitored, providing us with distinct punctual sources that could be localized beyond the diffraction limit. We previously showed experimentally that resolutions beyond λ/10 can be reached in ultrafast ultrasound localization microscopy (uULM) using a 128 transducer matrix in reception. Higher resolutions are theoretically achievable and the aim of this study is to predict the maximum resolution in uULM with respect to acquisition parameters (frequency, transducer geometry, sampling electronics). The accuracy of uULM is the error on the localization of a bubble, considered a point-source in a homogeneous medium. The proposed model consists in two steps: determining the timing accuracy of the microbubble echo in radiofrequency data, then transferring this time accuracy into spatial accuracy. The simplified model predicts a maximum resolution of 40 μm for a 1.75 MHz transducer matrix composed of two rows of 64 elements. Experimental confirmation of the model was performed by flowing microbubbles within a 60 μm microfluidic channel and localizing their blinking under ultrafast imaging (500 Hz frame rate). The experimental resolution, determined as the standard deviation in the positioning of the microbubbles, was predicted within 6 μm (13%) of the theoretical values and followed the analytical relationship with respect to the number of elements and depth. Understanding the underlying physical principles determining the resolution of superlocalization will allow the optimization of the imaging setup for each organ. Ultimately, accuracies better than the size of capillaries are achievable at several centimeter depths.
Polygonal instabilities on interfacial vorticities.
Labousse, M., and J. W. M. Bush.
European Physical Journal E 38, no. 10 (2015): 1–11.
Multiplane wave imaging increases signal-to-noise ratio in ultrafast ultrasound imaging.
Tiran, E., T. Deffieux, M. Correia, D. Maresca, B. - F. Osmanski, L. - A. Sieu, A. Bergel, I. Cohen, M. Pernot, and M. Tanter.
Physics in medicine and biology 60, no. 21 (2015): 8549–66.
Placental elastography in a murine intrauterine growth restriction model.
Quibel, T., B. Deloison, F. Chammings, G. E. Chalouhi, N. Siauve, M. Alison, B. Bessières, J. L. Gennisson, O. Clément, and L. J. Salomon.
Prenatal Diagnosis 35, no. 11 (2015): 1106–1111.
Chiral route to pulling optical forces and left-handed optical torques.
Physical Review A 92, no. 4 (2015).
Photoacoustic generation by a gold nanosphere: From linear to nonlinear thermoelastics in the long-pulse illumination regime.
Prost, A., F. Poisson, and E. Bossy.
Physical Review B – Condensed Matter and Materials Physics 92, no. 11 (2015).
Résumé: © 2015 American Physical Society. We investigate theoretically the photoacoustic generation by a gold nanosphere in water in the thermoelastic regime. Specifically, we consider the long-pulse illumination regime, in which the time for electron-phonon thermalization can be neglected and photoacoustic wave generation arises solely from the thermoelastic stress caused by the temperature increase of the nanosphere or its liquid environment. Photoacoustic signals are predicted based on the successive resolution of a thermal diffusion problem and a thermoelastic problem, taking into account the finite size of the gold nanosphere, thermoelastic and elastic properties of both water and gold, and the temperature dependence of the thermal expansion coefficient of water. For sufficiently high illumination fluences, this temperature dependence yields a nonlinear relationship between the photoacoustic amplitude and the fluence. For nanosecond pulses in the linear regime, we show that more than 90% of the emitted photoacoustic energy is generated in water, and the thickness of the generating layer around the particle scales close to the square root of the pulse duration. The amplitude of the photoacoustic wave in the linear regime is accurately predicted by the point-absorber model introduced by Calasso et al. [Phys. Rev. Lett. 86, 3550 (2001)PRLTAO0031-900710.1103/PhysRevLett.86.3550], but our results demonstrate that this model significantly overestimates the amplitude of photoacoustic waves in the nonlinear regime. We therefore provide quantitative estimates of a critical energy, defined as the absorbed energy required such that the nonlinear contribution is equal to that of the linear contribution. Our results suggest that the critical energy scales as the volume of water over which heat diffuses during the illumination pulse. Moreover, thermal nonlinearity is shown to be expected only for sufficiently high ultrasound frequency. Finally, we show that the relationship between the photoacoustic amplitude and the equilibrium temperature at sufficiently high fluence reflects the thermal diffusion at the nanoscale around the gold nanosphere.
Cardiac shear-wave elastography using a transesophageal transducer: application to the mapping of thermal lesions in ultrasound transesophageal cardiac ablation.
Kwiecinski, W., F. Bessiere, E. C. Colas, W. Apoutou N'djin, M. Tanter, C. Lafon, and M. Pernot.
Physics in medicine and biology 60, no. 20 (2015): 7829–46.
Assessment of the cervix in pregnant women using shear wave elastography: A feasibility study.
Muller, M., D. Aït-Belkacem, M. Hessabi, J. L. Gennisson, G. Grangé, G. Grangé, F. Goffinet, F. Goffinet, F. Goffinet, E. Lecarpentier et al.
Ultrasound in Medicine and Biology 41, no. 11 (2015): 2789–2797.
Résumé: © 2015 World Federation for Ultrasound in Medicine and Biology. The quantitative assessment of the cervix is crucial for the estimation of pre-term delivery risk and the prediction of the success of labor induction. We conducted a cross-sectional study using shear wave elastography based on the supersonic shear imaging technique. The shear wave speed (SWS) of the lower anterior part of the cervix was quantified over an 8-mm region of interest in 157 pregnant women. Cervical SWS is slightly but significantly reduced in patients diagnosed with pre-term labor and in patients who actually delivered pre-term.
Hypothermic Total Liquid Ventilation Is Highly Protective Through Cerebral Hemodynamic Preservation and Sepsis-Like Mitigation After Asphyxial Cardiac Arrest.
Kohlhauer, M., F. Lidouren, I. Remy-Jouet, N. Mongardon, C. Adam, P. Bruneval, H. Hocini, Y. Levy, F. Blengio, P. Carli et al.
Critical care medicine 43, no. 10 (2015): e420–30.
Discriminative imaging of maternal and fetal blood flow within the placenta using ultrafast ultrasound.
Osmanski, B. - F., E. Lecarpentier, G. Montaldo, V. Tsatsaris, P. Chavatte-Palmer, and M. Tanter.
Scientific reports 5 (2015): 13394.
In Vivo Evaluation of Cervical Stiffness Evolution during Induced Ripening Using Shear Wave Elastography, Histology and 2 Photon Excitation Microscopy: Insight from an Animal Model.
Peralta, L., E. Mourier, C. Richard, G. Charpigny, T. Larcher, D. Ait-Belkacem, N. K. Balla, S. Brasselet, M. Tanter, M. Muller et al.
Plos One 10, no. 8 (2015).
EEG and functional ultrasound imaging in mobile rats.
Sieu, L. A., L. A. Sieu, A. Bergel, A. Bergel, E. Tiran, T. Deffieux, M. Pernot, J. L. Gennisson, M. Tanter, and I. Cohen.
Nature Methods 12, no. 9 (2015): 831–834.
Résumé: © 2015 Nature America, Inc. We developed an integrated experimental framework that extends the brain exploration capabilities of functional ultrasound imaging to awake and mobile rats. In addition to acquiring hemodynamic data, this method further allows parallel access to electroencephalography (EEG) recordings of neuronal activity. We illustrate this approach with two proofs of concept: a behavioral study on theta rhythm activation in a maze running task and a disease-related study on spontaneous epileptic seizures.
Tuning the wavelength of spoof plasmons by adjusting the impedance contrast in an array of penetrable inclusions.
Cordero, M. L., A. Maurel, J. F. Mercier, S. Félix, and F. Barra.
Applied Physics Letters 107, no. 8 (2015).
Résumé: © 2015 AIP Publishing LLC. While spoof plasmons have been proposed in periodic arrays of sound-hard inclusions, we show that they also exist when inclusions are penetrable. Moreover, we show that their wavelength can be tuned by the impedance mismatch between the inclusion material and the surrounding medium, beyond the usual effect of filling fraction in the array. It is demonstrated that sound-soft materials increase the efficiency in the generation of sub-wavelength plasmons, with much lower wavelengths than sound-hard materials and than a homogeneous slab. An application to the generation of acoustic spoof plasmons by an ultra compact array of air/polydimethylsiloxane inclusions in water is proposed with plasmon wavelength tunable up to deep sub-wavelength scales.
Direct optical nanoscopy with axially localized detection.
Bourg, N., N. Bourg, C. Mayet, G. Dupuis, T. Barroca, P. Bon, S. Lécart, E. Fort, S. Lévêque-Fort, and S. Lévêque-Fort.
Nature Photonics 9, no. 9 (2015): 587–593.
Résumé: © 2015 Macmillan Publishers Limited. Evanescent light excitation is widely used in super-resolution fluorescence microscopy to confine light and reduce background noise. Here, we propose a method of exploiting evanescent light in the context of emission. When a fluorophore is located in close proximity to a medium with a higher refractive index, its near-field component is converted into light that propagates beyond the critical angle. This so-called supercritical-angle fluorescence can be captured using a high-numerical-aperture objective and used to determine the axial position of the fluorophore with nanometre precision. We introduce a new technique for three-dimensional nanoscopy that combines direct stochastic optical reconstruction microscopy (dSTORM) with dedicated detection of supercritical-angle fluorescence emission. We demonstrate that our approach of direct optical nanoscopy with axially localized detection (DONALD) typically yields an isotropic three-dimensional localization precision of 20nm within an axial range of ∼150nm above the coverslip.
Influence of nanoscale temperature rises on photoacoustic generation: Discrimination between optical absorbers based on thermal nonlinearity at high frequency.
Simandoux, O., A. Prost, J. Gateau, and E. Bossy.
Photoacoustics 3, no. 1 (2015): 20–25.
Résumé: © 2014 The Authors. In this work, we experimentally investigate thermal-based nonlinear photoacoustic generation as a mean to discriminate between different types of absorbing particles. The photoacoustic generation from solutions of dye molecules and gold nanospheres (same optical densities) was detected using a high frequency ultrasound transducer (20. MHz). Photoacoustic emission was observed with gold nanospheres at low fluence for an equilibrium temperature around 4. °C, where the linear photoacoustic effect in water vanishes, highlighting the nonlinear emission from the solution of nanospheres. The photoacoustic amplitude was also studied as a function of the equilibrium temperature from 2. °C to 20. °C. While the photoacoustic amplitude from the dye molecules vanished around 4. °C, the photoacoustic amplitude from the gold nanospheres remained significant over the whole temperature range. Our preliminary results suggest that in the context of high frequency photoacoustic imaging, nanoparticles may be discriminated from molecular absorbers based on nanoscale temperature rises.
Strong Modification of Magnetic Dipole Emission through Diabolo Nanoantennas.
Mivelle, M., T. Grosjean, G. W. Burr, U. C. Fischer, and M. F. Garcia-Parajo.
ACS Photonics 2, no. 8 (2015): 1071–1076.
Résumé: © 2015 American Chemical Society. Magnetic dipole transitions in matter are known to be orders of magnitude weaker than their electric dipole counterparts. Nanophotonic and plasmonic structures have the potential of strongly enhancing the optical magnetic fields in the near field, making these nanostructures ideal candidates to control and enhance the emission of magnetic dipole transitions. Here we theoretically investigate the potential of resonant optical nanoantennas based on diabolo and on metal-insulator-metal diabolo configurations to strongly modify the magnetic dipole of emitters. We find that both configurations provide unprecedented 10<sup>2</sup>- to 10<sup>3</sup>-fold enhancement of the total and the radiative decay rates of a magnetic dipole moment. We show that these two nanoantennas have opposed effects on the quantum yield of the magnetic dipole, translating into different antenna efficiencies. Furthermore, by using a magnetic dipole moment as a theoretical optical nanosensor, we numerically mapped the behavior of the magnetic local density of states (MLDOS) in the entire plane close to the diabolo nanoantenna. We demonstrate the strong confinement and local enhancement of the MLDOS by the nanoantenna. As such, these results underscore the unique ability of optical nanoantennas to control light emission from magnetic dipoles, opening new technological avenues in the magneto-optical domain.
Revealing the Cu<sup>2+</sup> ions localization at low symmetry Bi sites in photorefractive Bi<inf>12</inf>GeO<inf>20</inf> crystals doped with Cu and v by high frequency EPR.
Nistor, S. V., M. Stefan, E. Goovaerts, F. Ramaz, and B. Briat.
Journal of Magnetic Resonance 259 (2015): 87–94.
Résumé: © 2015 Elsevier Inc. All rights reserved. The sites of incorporation of Cu<sup>2+</sup> impurity ions in Bi<inf>12</inf>GeO<inf>20</inf> single crystals co-doped with copper and vanadium have been investigated by electron paramagnetic resonance (EPR). While the X-band EPR spectra consist of a simple broad (ΔB ∼50 mT) line with anisotropic lineshape, the W-band EPR spectra exhibit well resolved, strongly anisotropic lines, due to transitions within the 3d<sup>9</sup>-<sup>2</sup>D ground manifold of the Cu<sup>2+</sup> ions. The most intense group of lines, attributed to the dominant Cu<sup>2+</sup>(I) center, displays a characteristic four components hyperfine structure for magnetic field orientations close to a (1 1 0) direction. The g and A tensor main axes are very close to one of the 12 possible sets of orthogonal (1-1 0), (0 0-1) and (1 1 0) crystal directions. Several less intense lines, with unresolved hyperfine structure and similar symmetry properties, mostly overlapped by the Cu<sup>2+</sup>(I) spectrum, were attributed to Cu<sup>2+</sup>(II) centers. The two paramagnetic centers are identified as substitutional Cu<sup>2+</sup> ions at Bi<sup>3+</sup> sites with low C<inf>1</inf> symmetry, very likely resulting from different configurations of neighboring charge compensating defects.
3-D ultrafast doppler imaging applied to the noninvasive mapping of blood vessels in Vivo.
Provost, J., C. Papadacci, C. Demene, J. L. Gennisson, M. Tanter, and M. Pernot.
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 62, no. 8 (2015): 1467–1472.
Résumé: © 2014 IEEE. Ultrafast Doppler imaging was introduced as a technique to quantify blood flow in an entire 2-D field of view, expanding the field of application of ultrasound imaging to the highly sensitive anatomical and functional mapping of blood vessels. We have recently developed 3-D ultrafast ultrasound imaging, a technique that can produce thousands of ultrasound volumes per second, based on a 3-D plane and diverging wave emissions, and demonstrated its clinical feasibility in human subjects in vivo. In this study, we show that noninvasive 3-D ultrafast power Doppler, pulsed Doppler, and color Doppler imaging can be used to perform imaging of blood vessels in humans when using coherent compounding of 3-D tilted plane waves. A customized, programmable, 1024-channel ultrasound system was designed to perform 3-D ultrafast imaging. Using a 32 × 32, 3-MHz matrix phased array (Vermon, Tours, France), volumes were beamformed by coherently compounding successive tilted plane wave emissions. Doppler processing was then applied in a voxel-wise fashion. The proof of principle of 3-D ultrafast power Doppler imaging was first performed by imaging Tygon tubes of various diameters, and in vivo feasibility was demonstrated by imaging small vessels in the human thyroid. Simultaneous 3-D color and pulsed Doppler imaging using compounded emissions were also applied in the carotid artery and the jugular vein in one healthy volunteer.
Elastography of multicellular aggregates submitted to osmo-mechanical stress.
Leroux, C. E., J. Palmier, A. C. Boccara, G. Cappello, and S. Monnier.
New Journal of Physics 17, no. 7 (2015).
Résumé: © 2015 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. Tumors are subjected to mechanical stress generated by their own growth in a confined environment, and by their surrounding tissues. Recent works have focused on the study of the growth of spherical aggregates of cells, spheroids, under controlled confinement or stress. In this study we demonstrate the measurement of spatially and temporally resolved deformation maps inside spheroids while applying an osmo-mechanical stress. We use full field optical coherence tomography, a high resolution imaging technique well suited for real-time measurements of deformation in living tissues under stress. Using the spherical symmetry of the experiment, we compare our data to a mechanical modeling of the spheroid as a continuous medium. We estimate the viscoelastic parameters of spheroids and discuss the apparent tissue anisotropy after the osmo-mechanical stress.
Carotid stiffness change over the cardiac cycle by ultrafast ultrasound imaging in healthy volunteers and vascular Ehlers-Danlos syndrome.
Mirault, T., M. Pernot, M. Frank, M. Couade, R. Niarra, M. Azizi, J. Emmerich, X. Jeunemaitre, M. Fink, M. Tanter et al.
Journal of hypertension 33, no. 9 (2015): 1890–6.
The Use of Ultrasound to Measure Dislocation Density.
Barra, F., R. Espinoza-Gonzalez, H. Fernandez, F. Lund, A. Maurel, and V. Pagneux.
Jom 67, no. 8 (2015): 1856–1863.
Reliable Protocol for Shear Wave Elastography of Lower Limb Muscles at Rest and During Passive Stretching.
Dubois, G., W. Kheireddine, C. Vergari, D. Bonneau, P. Thoreux, P. Thoreux, P. Rouch, M. Tanter, J. L. Gennisson, and W. Skalli.
Ultrasound in Medicine and Biology 41, no. 9 (2015): 2284–2291.
Résumé: © 2015 World Federation for Ultrasound in Medicine & Biology. Development of shear wave elastography gave access to non-invasive muscle stiffness assessment in vivo. The aim of the present study was to define a measurement protocol to be used in clinical routine for quantifying the shear modulus of lower limb muscles. Four positions were defined to evaluate shear modulus in 10 healthy subjects: parallel to the fibers, in the anterior and posterior aspects of the lower limb, at rest and during passive stretching. Reliability was first evaluated on two muscles by three operators; these measurements were repeated six times. Then, measurement reliability was compared in 11 muscles by two operators; these measurements were repeated three times. Reproducibility of shear modulus was 0.48 kPa and repeatability was 0.41 kPa, with all muscles pooled. Position did not significantly influence reliability. Shear wave elastography appeared to be an appropriate and reliable tool to evaluate the shear modulus of lower limb muscles with the proposed protocol.
Dark-field full-field optical coherence tomography.
Optics Letters 40, no. 14 (2015): 3272–3275.
Observation of the internal response of the kidney during compressive loading using ultrafast ultrasonography.
Helfenstein-Didier, C., C. Helfenstein-Didier, C. Helfenstein-Didier, M. Tanter, J. L. Gennisson, P. Beillas, P. Beillas, and P. Beillas.
Journal of Biomechanics 48, no. 10 (2015): 1852–1859.
Résumé: © 2015 Elsevier Ltd. A protocol based on ultrafast ultrasonography was developed to study the internal response of isolated perfused human (n=3) and porcine (n=11) kidneys subjected to loading at 0.003 m/s and 0.3 m/s respectively. Regional uniaxial strains were calculated based on natural target tracking. The effect of loading speed and regional differences could be statistically detected on the porcine specimens. However, despite the inhomogeneity of their anatomical structures, strains' responses appeared relatively homogeneous at 0.3 m/s in both porcine and human kidneys.Failure, identified as a sudden change on the ultrasonography movie, also appeared at similar compression levels for both species (38.3% of applied strain in average for human and 35.8% of applied strain in average for porcine).
Three-dimensional nanometre localization of nanoparticles to enhance super-resolution microscopy.
Bon, P., N. Bourg, S. Lecart, S. Monneret, E. Fort, J. Wenger, and S. Leveque-Fort.
Nature communications 6 (2015): 7764.
Experimental demonstration of epsilon-near-zero water waves focusing.
Bobinski, T., A. Eddi, P. Petitjeans, A. Maurel, and V. Pagneux.
Applied Physics Letters 107, no. 1 (2015).
Résumé: © 2015 AIP Publishing LLC. We explore an ε-near-zero analogue for water waves using deep water and shallow water domains to obtain different phase velocities. Being inherently non linear, water waves permit to inspect focusing of harmonically generated waves. Experimental measurements show cascade of focal spots up to the fourth harmonic, allowing sub wavelength focusing with respect to the first harmonic wavelength.
Mechanical induction of the tumorigenic beta-catenin pathway by tumour growth pressure.
Fernandez-Sanchez, M. E., S. Barbier, J. Whitehead, G. Bealle, A. Michel, H. Latorre-Ossa, C. Rey, L. Fouassier, A. Claperon, L. Brulle et al.
Nature 523, no. 7558 (2015): 92–+.
Gennisson, J. - L., J. Provost, T. Deffieux, C. Papadacci, M. Imbault, M. Pernot, and M. Tanter.
Ieee Transactions On Ultrasonics Ferroelectrics And Frequency Control 62, no. 6 (2015): 1059–1065.
Elastography for Muscle Biomechanics: Toward the Estimation of Individual Muscle Force.
Hug, F., K. Tucker, J. - L. Gennisson, M. Tanter, and A. Nordez.
Exercise and sport sciences reviews 43, no. 3 (2015): 125–33.
Bencteux, J., P. Pagnoux, T. Kostas, S. Bayat, and M. Atlan.
Journal of biomedical optics 20, no. 6 (2015): 66006.
Singular-value demodulation of phase-shifted holograms.
Lopes, F., and M. Atlan.
Optics Letters 40, no. 11 (2015): 2541–2544.
Holographic microscopy reconstruction in both object and image half-spaces with an undistorted three-dimensional grid.
Verrier, N., D. Alexandre, G. Tessier, and M. Gross.
Applied Optics 54, no. 15 (2015): 4672–4677.
Schott, S., J. Bertolotti, J. - F. Leger, L. Bourdieu, and S. Gigan.
Optics Express 23, no. 10 (2015): 13505–13516.
Modal method for the 2D wave propagation in heterogeneous anisotropic media.
Maurel, A., J. - F. Mercier, and S. Felix.
Journal Of The Optical Society Of America A-Optics Image Science And Vision 32, no. 5 (2015): 979–990.
Single-side access, isotropic resolution, and multispectral three-dimensional photoacoustic imaging with rotate-translate scanning of ultrasonic detector array.
Gateau, J., M. Gesnik, J. - M. Chassot, and E. Bossy.
Journal of biomedical optics 20, no. 5 (2015): 56004.
Sound propagation in liquid foams: Unraveling the balance between physical and chemical parameters.
Pierre, J., B. Giraudet, P. Chasle, B. Dollet, and A. St-Jalmes.
Physical Review E 91, no. 4 (2015).
Propagation of elastic waves through textured polycrystals: application to ice.
Maurel, A., F. Lund, and M. Montagnat.
Proceedings Of The Royal Society A-Mathematical Physical And Engineering Sciences 471, no. 2177 (2015).
A fast and switchable microfluidic mixer based on ultrasound-induced vaporization of perfluorocarbon.
Bezagu, M., M. Bezagu, S. Arseniyadis, J. Cossy, O. Couture, M. Tanter, F. Monti, and P. Tabeling.
Lab on a Chip – Miniaturisation for Chemistry and Biology 15, no. 9 (2015): 2025–2029.
Résumé: This journal is © The Royal Society of Chemistry 2015. Mixing two fluids together within a microfluidic device still remains a challenging operation today. In order to achieve this goal, a number of effective micromixers have been developed over the years based on the use of either passive or active systems. Typically, passive mixers require no external energy, are more robust, and are easy to manufacture albeit they are poorly flexible. Active mixers, on the other hand, rely on external disturbance and are thus more difficult to use but are proven to have greater efficacy. Here, we report a particularly effective, remotely induced and switchable microfluidic mixer, which relies on the concomitant use of ultrasound and a perfluorocarbon (PFC) phase, with the latter benefiting from its immiscibility with most fluids and its low boiling point. More specifically, our approach is based on localized vaporization of a PFC phase at the focal zone of a transducer leading to efficient mixing of two adjacent fluids. The results show that mixing occurs ~100 ms following the delivery of the acoustic pulse, while a laminar flow is re-established on roughly the same time scale. Overall, this method is simple and effective, does not require tailored channel geometries, is compatible with both hydrophilic and hydrophobic microfluidic systems, and is applicable to a wide range of Reynolds numbers (10<sup>-4</sup> < Re < 2.10<sup>0</sup>), and the PFC phase can be easily separated from the mixed phase at the end of the run.
Directional cloaking of flexural waves in a plate with a locally resonant metamaterial.
Colombi, A., P. Roux, S. Guenneau, and M. Rupin.
Journal of the Acoustical Society of America 137, no. 4 (2015): 1783–1789.
Résumé: © 2015 Acoustical Society of America. This paper deals with the numerical design of a directional invisibility cloak for backward scattered elastic waves propagating in a thin plate (A<inf>0</inf> Lamb waves). The directional cloak is based on a set of resonating beams that are attached perpendicular to the plate and are arranged at a sub-wavelength scale in ten concentric rings. The exotic effective properties of this locally resonant metamaterial ensure coexistence of bandgaps and directional cloaking for certain beam configurations over a large frequency band. The best directional cloaking was obtained when the resonators' length decreases from the central to the outermost ring. In this case, flexural waves experience a vanishing index of refraction when they cross the outer layers, leading to a frequency bandgap that protects the central part of the cloak. Numerical simulation shows that there is no back-scattering in these configurations. These results might have applications in the design of seismic-wave protection devices.
Modelling the impulse diffraction field of shear waves in transverse isotropic viscoelastic medium.
Chatelin, S., J. L. Gennisson, M. A. Bernal, M. Tanter, and M. Pernot.
Physics in Medicine and Biology 60, no. 9 (2015): 3639–3654.
Résumé: © 2015 Institute of Physics and Engineering in Medicine. The generation of shear waves from an ultrasound focused beam has been developed as a major concept for remote palpation using shear wave elastography (SWE). For muscular diagnostic applications, characteristics of the shear wave profile will strongly depend on characteristics of the transducer as well as the orientation of muscular fibers and the tissue viscoelastic properties. The numerical simulation of shear waves generated from a specific probe in an anisotropic viscoelastic medium is a key issue for further developments of SWE in fibrous soft tissues. In this study we propose a complete numerical tool allowing 3D simulation of a shear wave front in anisotropic viscoelastic media. From the description of an ultrasonic transducer, the shear wave source is simulated by using Field's II software and shear wave propagation described by using the Green's formalism. Finally, the comparison between simulations and experiments are successively performed for both shear wave velocity and dispersion profile in a transverse isotropic hydrogel phantom, in vivo forearm muscle and in vivo biceps brachii.
Out-of-plane doppler imaging based on ultrafast plane wave imaging.
Osmanski, B. F., G. Montaldo, and M. Tanter.
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 62, no. 4 (2015): 625–636.
Résumé: © 1986-2012 IEEE. Retrieving the out-of-plane blood flow velocity vector from two-dimensional transverse acquisitions of large vessels could improve the quantification of flow rate and maximum speed. The in-plane vector flow component can be computed easily using the Doppler frequency shift. The main problem is estimating the angle between the probe imaging plane and the vessel axis to derive the out-of-plane component from in-plane measurements. In this article, we study the case in which the velocity vector can be decomposed on two directions: the out-of-plane direction and the in-plane depth direction. We explore the combination of a technique called intrinsic spectral broadening with ultrafast plane wave imaging to retrieve the out-of-plane component of the flow velocity vector. Using a one-time probe calibration of this intrinsic spectral broadening, out-of-plane angle and flow speed can be recovered easily, thus avoiding approximations of a complex theoretical analysis. For the calibration step, ultrafast plane wave imaging permits a fast calibration procedure for the Doppler intrinsic spectral broadening. In vitro experimental validations are performed on a homogeneous flow phantom and a Poiseuille flow; the absolute speed was retrieved with 6% error. The potential of the technique is demonstrated in vivo on the human carotid artery. Combined with in-plane vector flow approaches, this out-of-plane Doppler imaging method paves the way to threedimensional vector flow imaging using only conventional onedimensional probe technology.
Ultrashort echo-time MRI versus CT for skull aberration correction in MR-guided transcranial focused ultrasound: In vitro comparison on human calvaria.
Miller, G. W., M. D. C. Eames, J. Snell, and J. F. Aubry.
Medical Physics 42, no. 5 (2015): 2223–2233.
Résumé: ©2015 American Association of Physicists in Medicine. Purpose: Transcranial magnetic resonance-guided focused ultrasound (TcMRgFUS) brain treatment systems compensate for skull-induced beam aberrations by adjusting the phase and amplitude of individual ultrasound transducer elements. These corrections are currently calculated based on a preacquired computed tomography (CT) scan of the patients head. The purpose of the work presented here is to demonstrate the feasibility of using ultrashort echo-time magnetic resonance imaging (UTE MRI) instead of CT to calculate and apply aberration corrections on a clinical TcMRgFUS system. Methods: Phantom experiments were performed in three ex-vivo human skulls filled with tissuemimicking hydrogel. Each skull phantom was imaged with both CT and UTE MRI. The MR images were then segmented into skull and not-skull pixels using a computationally efficient, thresholdbased algorithm, and the resulting 3D binary skull map was converted into a series of 2D virtual CT images. Each skull was mounted in the head transducer of a clinical TcMRgFUS system (ExAblate Neuro, Insightec, Israel), and transcranial sonications were performed using a power setting of approximately 750 acousticwatts at several different target locations within the electronic steering range of the transducer. Each target locationwas sonicated three times: once using aberration corrections calculated from the actual CT scan, once using corrections calculated from the MRI-derived virtual CT scan, and once without applying any aberration correction.MRthermometry was performed in conjunction with each 10-s sonication, and the highest single-pixel temperature rise and surrounding-pixel mean were recorded for each sonication. Results: The measured temperature rises were ∼45% larger for aberration-corrected sonications than for noncorrected sonications. This improvement was highly significant (p < 10?4). The difference between the single-pixel peak temperature rise and the surrounding-pixel mean, which reflects the sharpness of the thermal focus,was also significantly larger for aberration-corrected sonications. There was no significant difference between the sonication results achieved using CT-based and MR-based aberration correction. Conclusions: The authors have demonstrated that transcranial focal heating can be significantly improved in vitro by usingUTEMRIto compute skull-induced ultrasound aberration corrections. Their results suggest that UTE MRI could be used instead of CT to implement such corrections on current 0.7MHzclinical TcMRgFUS devices. TheMRimage acquisition and segmentation procedure demonstrated here would add less than 15 min to a clinical MRgFUS treatment session.
Wave propagation in a waveguide containing restrictions with circular arc shape.
Félix, S., A. Maurel, and J. F. Mercier.
Journal of the Acoustical Society of America 137, no. 3 (2015): 1274–1281.
Résumé: © 2015 Acoustical Society of America. A multimodal method is used to analyze the wave propagation in waveguides containing restrictions (or corrugations) with circular arc shapes. This is done using a geometrical transformation which transforms the waveguide with complex geometry in the real space to a straight waveguide in the transformed space, or virtual space. In this virtual space, the Helmholtz equation has a modified structure which encapsulates the complexity of the geometry. It is solved using an improved modal method, which was proposed in a paper by A. Maurel, J.-F. Mercier, and S. Félix [Proc. R. Soc. A 470, 20130743 (2014)], that increases the accuracy and convergence of usual multimodal formulations. Results show the possibility to solve the wave propagation in a waveguide with a high density of circular arc shaped scatterers.
A versatile and experimentally validated finite element model to assess the accuracy of shear wave elastography in a bounded viscoelastic medium.
Caenen, A., D. A. Shcherbakova, B. Verhegghe, C. Papadacci, M. Pernot, P. F. Segers, and A. E. S. Swillens.
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 62, no. 3 (2015): 439–450.
Résumé: © 1986-2012 IEEE. The feasibility of shear wave elastography (SWE) in arteries for cardiovascular risk assessment remains to be investigated as the artery's thin wall and intricate material properties induce complex shear wave (SW) propagation phenomena. To better understand the SW physics in bounded media, we proposed an in vitro validated finite element model capable of simulating SW propagation, with full flexibility at the level of the tissue's geometry, material properties, and acoustic radiation force. This computer model was presented in a relatively basic set-up, a homogeneous slab of gelatin-agar material (4.35 mm thick), allowing validation of the numerical settings according to actual SWE measurements. The resulting tissue velocity waveforms and SW propagation speed matched well with the measurement: 4.46 m/s (simulation) versus 4.63 ± 0.07 m/s (experiment). Further, we identified the impact of geometrical and material parameters on the SW propagation characteristics. As expected, phantom thickness was a determining factor of dispersion. Adding viscoelasticity to the model augmented the estimated wave speed to 4.58 m/s, an even better match with the experimental determined value. This study demonstrated that finite element modeling can be a powerful tool to gain insight into SWE mechanics and will in future work be advanced to more clinically relevant settings.
Eames, M. D. C., M. Farnum, M. A. Khaled, W. Jeff Elias, A. Hananel, J. W. Snell, N. F. M. D. Kassell, and J. F. Aubry.
Medical Physics 42, no. 4 (2015): 1518–1527.
Résumé: © 2015 American Association of Physicists in Medicine. Purpose: In the ongoing endeavor of fine-tuning, the clinical application of transcranial MR-guided focused ultrasound (tcMRgFUS), ex-vivo studies wlkiith whole human skulls are of great use in improving the underlying technology guiding the accurate and precise thermal ablation of clinically relevant targets in the human skull. Described here are the designs, methods for fabrication, and notes on utility of three different ultrasound phantoms to be used for brain focused ultrasound research. Methods: Three different models of phantoms are developed and tested to be accurate, repeatable experimental options to provide means to further this research. The three models are a cadaver, a gel-filled skull, and a head mold containing a skull and filled with gel that mimics the brain and the skin. Each was positioned in a clinical tcMRgFUS system and sonicated at 1100 W (acoustic) for 12 s at different locations. Maximum temperature rise as measured by MR thermometry was recorded and compared against clinical data for a similar neurosurgical target. Results are presented as heating efficiency in units (°C/kW/s) for direct comparison to available clinical data. The procedure for casting thermal phantom material is presented. The utility of each phantom model is discussed in the context of various tcMRgFUS research areas. Results: The cadaveric phantom model, gel-filled skull model, and full head phantom model had heating efficiencies of 5.3, 4.0, and 3.9 °C/(kW/s), respectively, compared to a sample clinical heating efficiency of 2.6 °C/(kW/s). In the seven research categories considered, the cadaveric phantom model was the most versatile, though less practical compared to the ex-vivo skull-based phantoms. Conclusions: Casting thermal phantom material was shown to be an effective way to prepare tissue-mimicking material for the phantoms presented. The phantom models presented are all useful in tcMRgFUS research, though some are better suited to a limited subset of applications depending on the researchers needs.
Disorder persistent transparency within the bandgap of a periodic array of acoustic Helmholtz resonators.
Richoux, O., A. Maurel, and V. Pagneux.
Journal of Applied Physics 117, no. 10 (2015).
Résumé: © 2015 AIP Publishing LLC. In this paper, the influence of disorder on 1D periodic lattice of resonant scatterers is inspected. These latter have multiple resonance frequencies which produce band gaps in the transmission spectrum. One peculiarity of the presented system is that it is chosen with a nearly perfect overlap between the Bragg and the second hybridization band gaps. In the case of a perfectly ordered lattice, and around this overlap, this produces a narrow transparency band within a large second bandgap. As expected, the effect of the disorder is generally to increase the width of the band gaps. Nevertheless, the transparency band appears to be robust with respect to an increase in the disorder. In this paper, we study this effect by means of experimental investigations and numerical simulations.
Scanning-free imaging through a single fiber by random spatio-spectral encoding.
Kolenderska, S. M., O. Katz, M. Fink, and S. Gigan.
Optics Letters 40, no. 4 (2015): 534–537.
Résumé: © 2015 Optical Society of America. We present an approach for 2D imaging through a single fiber without the need for scanners. A random scattering medium placed next to the distal end of the fiber is used to encode the collected light from every imaged pixel with a different random spectral signature. We demonstrate imaging of externally illuminated 2D objects from a single measured spectrum at the fiber's proximal end. The technique is insensitive to fiber bending, an advantage for endoscopic applications.
Fourier transform acousto-optic imaging with a custom-designed CMOS smart-pixels array.
Barjean, K., K. Contreras, J. B. Laudereau, E. Tinet, D. Ettori, F. Ramaz, and J. M. Tualle.
Optics Letters 40, no. 5 (2015): 705–708.
Résumé: © 2015 Optical Society of America. We report acousto-optic imaging (AOI) into a scattering medium using a Fourier Transform (FT) analysis to achieve axial resolution. The measurement system was implemented using a CMOS smart-pixels sensor dedicated to the real-time analysis of speckle patterns. This first proof-of-principle of FT-AOI demonstrates some of its potential advantages, with a signal-to-noise ratio comparable to the one obtained without axial resolution, and with an acquisition rate compatible with a use on living biological tissue.
Optical-resolution photoacoustic imaging through thick tissue with a thin capillary as a dual optical-in acoustic-out waveguide.
Simandoux, O., N. Stasio, J. Gâteau, J. P. Huignard, C. Moser, D. Psaltis, and E. Bossy.
Applied Physics Letters 106, no. 9 (2015).
Résumé: © 2015 AIP Publishing LLC. We demonstrate the ability to guide high-frequency photoacoustic waves through thick tissue with a water-filled silica-capillary (150 μm inner diameter and 30 mm long). An optical-resolution photoacoustic image of a 30 μm diameter absorbing nylon thread was obtained by guiding the acoustic waves in the capillary through a 3 cm thick fat layer. The transmission loss through the capillary was about -20 dB, much lower than the -120 dB acoustic attenuation through the fat layer. The overwhelming acoustic attenuation of high-frequency acoustic waves by biological tissue can therefore be avoided by the use of a small footprint capillary acoustic waveguide for remote detection. We finally demonstrate that the capillary can be used as a dual optical-in acoustic-out waveguide, paving the way for the development of minimally invasive optical-resolution photoacoustic endoscopes free of any acoustic or optical elements at their imaging tip.
Viscoelasticity in Achilles Tendonopathy: Quantitative Assessment by Using Real-time Shear-Wave Elastography.
Aubry, S., J. - P. Nueffer, M. Tanter, F. Becce, C. Vidal, and F. Michel.
Radiology 274, no. 3 (2015): 821–9.
Experiments on Maxwell's fish-eye dynamics in elastic plates.
Lefebvre, G., M. Dubois, R. Beauvais, Y. Achaoui, R. K. Ing, S. Guenneau, and P. Sebbah.
Applied Physics Letters 106, no. 2 (2015).
Super-resolution experiments on Lamb waves using a single emitter.
Rupin, M., S. Catheline, and P. Roux.
Improved multimodal methods for the acoustic propagation in waveguides with finite wall impedance.
Wave Motion 54 (2015): 1–10.
Résumé: © 2014 Elsevier B.V. We address the problem of acoustic propagation in waveguides with wall impedance, or Robin, boundary condition. Two improved multimodal methods are developed to remedy the problem of the low convergence of the series in the standard modal approach. In the first improved method, the series is enriched with an additional mode, which is thought to be able to restore the right boundary condition. The second improved method consists in a reformulation of the expansions able to restore the right boundary conditions for any truncation, similar to polynomial subtraction technique. Surprisingly, the first improved method is found to be the most efficient. Notably, the convergence of the scattering properties is increased from N-1 in the standard modal method to N-3 in the reformulation and N-5 in the formulation with a supplementary mode. The improved methods are shown to be of particular interest when surface waves are generated near the impedance wall.
Ultrasonographic renal volume measurements in early autosomal dominant polycystic disease: Comparison with CT-scan renal volume calculations.
Hammoud, S., A. - M. Tissier, C. Elie, M. Pousset, B. Knebelman, D. Joly, O. Helenon, and J. - M. Correas.
Diagnostic And Interventional Imaging 96, no. 1 (2015): 65–71.
Investigating liver stiffness and viscosity for fibrosis, steatosis and activity staging using shear wave elastography.
Deffieux, T., J. - L. Gennisson, L. Bousquet, M. Corouge, S. Cosconea, D. Amroun, S. Tripon, B. Terris, V. Mallet, P. Sogni et al.
Journal of hepatology 62, no. 2 (2015): 317–24.
Super-resolution in time-reversal focusing on a moving source.
Garnier, J., and M. Fink.
Wave Motion 53 (2015): 80–93.
Résumé: © 2014 Elsevier B.V. This paper presents a detailed analysis of time-reversal experiments involving a moving point source that emits a pulse. Different configurations are addressed with full-aperture or partial-aperture time-reversal mirrors and with subsonic or supersonic sources. Doppler effects and lack of source-receiver reciprocity significantly affect the time-reversal refocusing when the velocity of the source becomes comparable as or larger than the speed of propagation. The main result is that refocusing can be enhanced when the velocity of the source becomes close to the speed of propagation compared to the classical diffraction-limited refocusing properties when the source does not move, and this super-resolution effect can be quantified by simple and explicit formulas.
Defining The Optimal Age For Focal Lesioning In A Rat Model Of Transcranial Hifu.
Zhang, Y., J. - F. Aubry, J. Zhang, Y. Wang, J. Roy, J. F. Mata, W. Miller, E. Dumont, M. Xie, K. Lee et al.
Ultrasound In Medicine And Biology 41, no. 2 (2015): 449–455.
Effects of pressure on the shear modulus, mass and thickness of the perfused porcine kidney.
Helfenstein, C., J. L. Gennisson, M. Tanter, and P. D. Beillas.
Journal of Biomechanics 48, no. 1 (2015): 30–37.
Résumé: © 2014 Elsevier Ltd. Eleven fresh ex vivo porcine kidneys were perfused in the artery, vein and ureter with degassed Dulbecco's Modified Eagle Medium (DMEM). The effect of perfusion pressure was evaluated using ten different pressures combinations. The shear modulus of the tissues was estimated during perfusion using shear wave elastography. The organ weight change was measured by a digital scale and cameras were used to follow the changes of the dimensions after each pressure combination. The effect of perfusion on the weight and the thickness was non-reversible, whereas the effect on the shear modulus was reversible. Pressure was found to increase the average shear modulus in the cortex by as much as 73%. A pressure of 80mmHg was needed to observe tissues shear modulus in the same range as in vivo tests (Gcortex=9.1kPa, Gmedulla=8.5kPa ex vivo versus Gcortex=9.1kPa, Gmedulla=8.7kPa in vivo in Gennisson et al., 2012).
Non-Markovian polariton dynamics in organic strong coupling.
Canaguier-Durand, A., C. Genet, A. Lambrecht, T. W. Ebbesen, and S. Reynaud.
European Physical Journal D 69, no. 1 (2015).
Résumé: © EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2015. Strongly coupled organic systems are characterized by unusually large Rabi splitting, even in the vacuum state. They show the counter-intuitive feature of a lifetime of the lower polariton state longer than for all other excited states. Here we build up a new theoretical framework to understand the dynamics of such coupled system. In particular, we show that the non-Markovian character of the relaxation of the dressed organic system explains the long lifetime of the lower polariton state.
Retrieving time-dependent green's functions in optics with low-coherence interferometry.
Badon, A., G. Lerosey, A. C. Boccara, M. Fink, and A. Aubry.
Physical Review Letters 114, no. 2 (2015).
Résumé: © 2015 American Physical Society. We report on the passive measurement of time-dependent Green's functions in the optical frequency domain with low-coherence interferometry. Inspired by previous studies in acoustics and seismology, we show how the correlations of a broadband and incoherent wave field can directly yield the Green's functions between scatterers of a complex medium. Both the ballistic and multiple scattering components of the Green's function are retrieved. This approach opens important perspectives for optical imaging and characterization in complex scattering media.
Time-driven superoscillations with negative refraction.
Dubois, M. A., E. Bossy, S. Enoch, S. Guenneau, G. Lerosey, and P. Sebbah.
Physical Review Letters 114, no. 1 (2015).
Résumé: © 2015 American Physical Society. The flat-lens concept based on negative refraction proposed by Veselago in 1968 has been mostly investigated in the monochromatic regime. It was recently recognized that time development of the superlensing effect discovered in 2000 by Pendry is yet to be assessed and may spring surprises: Time-dependent illumination could improve the spatial resolution of the focusing. We investigate dynamics of flexural wave focusing by a 45°-tilted square lattice of circular holes drilled in a duralumin plate. Time-resolved experiments reveal that the focused image shrinks with time below the diffraction limit, with a lateral resolution increasing from 0.8λ to 0.35λ, whereas focusing under harmonic excitation remains diffraction limited. Modal analysis reveals the role in pulse reconstruction of radiating lens resonances, which repeatedly self-synchronize at the focal spot to shape a superoscillating field.
Xu, Z., C. Carlson, J. Snell, M. Eames, A. Hananel, M. B. Lopes, P. Raghavan, C. - C. Lee, C. - P. Yen, D. Schlesinger et al.
Journal Of Neurosurgery 122, no. 1 (2015): 152–161.

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