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Tours, France

Docter M.W.,Erasmus University Rotterdam | Beurskens R.H.S.H.,Erasmus University Rotterdam | Ferin G.,Vermon | Brands P.J.,ESAOTE Europe BV | And 2 more authors.
Proceedings - IEEE Ultrasonics Symposium | Year: 2010

We are developing a volumetric ultrasound system for high frame-rateimaging of the carotid artery. It will be used in early detection ofatherosclerosis, specifically aiming at visualization of neovascularizationinside vulnerable plaque. These small vessels will be visualized in 3D byharmonic imaging of ultrasound contrast agents. The main parts of the ultrasoundsystem are a 1024 element matrix array, a 128 channel transmitter-receiver andcustom multiplexer electronics. This paper discusses the design and results ofindividual elements and corresponding multiplexer channels of our prototypesystem. We measured a transmit bandwidth of 80%, a center frequency of 7.9 MHz,a pressure of 29 kPa/V at the transducer's surface, and >95% well-functioningelements, which meets our requirements. A volume frame rate of 1.9 kHz isachievable. © 2010 IEEE.

Boulme A.,University of Tours | Minonzio J.-G.,University Pierre and Marie Curie | Ngo S.,University of Tours | Legros M.,Vermon | And 8 more authors.
IEEE International Ultrasonics Symposium, IUS | Year: 2012

This paper presents the conception of a cMUTs probe for the cortical bone evaluation. A specific topology was designed in order to match the cMUTs technology to the requirements of the axial transmission measurement. We report here all the steps of the probe manufacturing from the design to the first post-process characterization of the cMUTs. The first results of axial transmission measurements performed on a bone mimicking plate are presented and compared with the ones obtained with the same probe in PZT technology. © 2012 IEEE.

Kwiecinski W.,ESPCI ParisTech | Provost J.,ESPCI ParisTech | Dubois R.,French Institute of Health and Medical Research | Sacher F.,French Institute of Health and Medical Research | And 6 more authors.
IRBM | Year: 2015

Atrial fibrillation is associated with increased risk of stroke and heart failure. Currently it can be treated with minimally invasive radio-frequency catheter ablation. However, the lack of monitoring and assessment of the transmural extent of the lesion currently limits the success rate of this technique. In this study we have developed a novel dual-mode intracardiac echocardiography catheter capable of performing ultrasound imaging and high-intensity focused ultrasound ablation. Using the same device we demonstrate in vivo the feasibility of intracardiac shear-wave elastography to evaluate thermal ablation as well as the feasibility of creating transmural and linear lesions (up to 10-mm wide) in the atrial wall. © 2015 Elsevier Masson SAS.

Legros M.,Vermon | Legros M.,French Institute of Health and Medical Research | Novell A.,French Institute of Health and Medical Research | Bouakaz A.,French Institute of Health and Medical Research | And 3 more authors.
IEEE International Ultrasonics Symposium, IUS | Year: 2011

In this work, we report on the characterization of a CMUT probe (Capactive Micromachined Ultrasound Transducer) for Tissue Harmonic Imaging (THI). The intrinsic nonlinear behavior of the CMUT probe was first investigated. Matched electrical waveforms were transmitted to limit the impact of the transmit response distortion. With the implemented method, we demonstrated higher performances through in-vitro harmonic imaging. © 2011 IEEE.

Kwiecinski W.,ESPCI ParisTech | Provost J.,ESPCI ParisTech | Dubois R.,French Institute of Health and Medical Research | Sacher F.,French Institute of Health and Medical Research | And 6 more authors.
Medical Physics | Year: 2014

Purpose: Radio frequency catheter ablation (RFCA) is a well-established clinical procedure for the treatment of atrial fibrillation (AF) but suffers from a low single-procedure success rate. Recurrence of AF is most likely attributable to discontinuous or nontransmural ablation lesions. Yet, despite this urgent clinical need, there is no clinically available imaging modality that can reliably map the lesion transmural extent in real time. In this study, the authors demonstrated the feasibility of shear-wave elastography (SWE) to map quantitatively the stiffness of RFCA-induced thermal lesions in cardiac tissues in vitro and in vivo using an intracardiac transducer array. Methods: SWE was first validated in ex vivo porcine ventricular samples (N = 5). Both B-mode imaging and SWE were performed on normal cardiac tissue before and after RFCA. Areas of the lesions were determined by tissue color change with gross pathology and compared against the SWE stiffness maps. SWE was then performed in vivo in three sheep (N = 3). First, the stiffness of normal atrial tissues was assessed quantitatively as well as its variation during the cardiac cycle. SWE was then performed in atrial tissue after RFCA. Results: A large increase in stiffness was observed in ablated ex vivo regions (average shear modulus across samples in normal tissue: 22±5 kPa, average shear-wave speed (ct): 4.5±0.4 m s-1 and in determined ablated zones: 99±17 kPa, average ct: 9.0±0.5 m s-1 for a mean shear modulus increase ratio of 4.5±0.9). In vivo, a threefold increase of the shear modulus was measured in the ablated regions, and the lesion extension was clearly visible on the stiffness maps. Conclusions: By its quantitative and real-time capabilities, Intracardiac SWE is a promising intraoperative imaging technique for the evaluation of thermal ablation during RFCA. © 2014 American Association of Physicists in Medicine.

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