Aberration correction by time reversal of moving speckle noise |
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Authors: | Bruno-Felix Osmanski Gabriel Montaldo Mickaël Tanter Mathias Fink |
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Affiliation: | Institut Langevin, Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris-ESPCI, ParisTech, Inserm U979, CNRS UMR7587, Universite Denis Diderot, France. bruno-felix.osmanski@espci.fr |
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Abstract: | Focusing a wave through heterogeneous media is an important problem in medical ultrasound imaging. In such aberrating media, in the presence of a small number of point reflectors, iterative time reversal is a well-known method able to focus on the strongest reflector. However, in presence of speckle noise generated by many non-resolved scatterers, iterative time reversal alone does not work. In this paper, we propose the use of the echoes coming from moving particles in a flow, such as red blood cells, to generate a virtual point reflector by iterative time reversal. The construction of the virtual point reflector is performed by a coherent addition of independent realizations of speckle coming from moving particles. After focusing on a virtual point reflector, ultrasound images can be locally corrected inside an isoplanatic patch. An application for the correction of power Doppler images is presented. A theoretical analysis shows that this iterative method allows focusing on the point of maximal insonification of the uncorrected beam. |
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