RECHERCHES Elastographie par ondes de cisaillement

Elastography is an imaging modality of Young’s Modulus of a biological medium (breast, liver,...). It consists of vibrating a medium and infer from the observed wavefield the distribution of elasticity. The displacement field is observed in the all volume. It thus requires to solve an inverse problem. We present an optimization approach which solves the problem by minimizing a discrepancy functional. When we want to recover a complex inclusion in homogenous medium, we notice that the information contained in the wavefield should be decomposed into two parts, a near field close from the inclusion and a far field part away from it. As we justify theoretically and numerically, separating these scales allows us have a local and precise reconstruction.

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Background: Epilepsy is a common neurological disorder, which is attributed to uncontrollable abnormal hyperexcitability of neurons. We investigated the feasibility of using low-intensity, pulsed radiation of focused ultrasound (FUS) to non-invasively suppress epileptic activity in an animal model (rat), which was induced by the intraperitonial injection of pentylenetetrazol (PTZ). Results: After the onset of induced seizures, FUS was transcranially administered to the brain twice for three minutes each while undergoing electroencephalographic (EEG) monitoring. An air-backed, spherical segment ultrasound transducer (diameter: 6 cm; radius-of-curvature: 7 cm) operating at a fundamental frequency of 690 KHz was used to deliver a train of 0.5 msec-long pulses of sonication at a repetitive rate of 100 Hz to the thalamic areas of the brain. The acoustic intensity (130 mW/cm 2) used in the experiment was sufficiently within the range of safety guidelines for the clinical ultrasound imaging. The occurrence of epileptic EEG bursts from epilepsy-induced rats significantly decreased after sonication when it was compared to the pre-sonication epileptic state. The PTZinduced control group that did not receive any sonication showed a sustained number of epileptic EEG signal bursts. The animals that underwent sonication also showed less severe epileptic behavior, as assessed by the Racine score. Histological analysis confirmed that the sonication did not cause any damage to the brain tissue.

Introduction: Shear wave elastography is a new method of obtaining quantitative tissue elasticity data during breast ultrasound examinations. The aims of this study were (1) to determine the reproducibility of shear wave elastography (2) to correlate the elasticity values of a series of solid breast masses with histological findings and (3) to compare shear wave elastography with greyscale ultrasound for benign/malignant classification. Methods: Using the Aixplorer ® ultrasound system (SuperSonic Imagine, Aix en Provence, France), 53 solid breast

ho sta Background There are several different medical imaging modalities Benign breast disease (BBD) is a well-known, significant risk factor for breast cancer [5]. BBD is diagnosed when Alizad et al. BMC Medical Imaging (2014) 14:40

stochastic filtering approach to recover strain images from quasi-static ultrasound elastography