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Problèmes inverses pour la cartographie optique cardiaque

Gwladys Ravon 1, 2
2 CARMEN - Modélisation et calculs pour l'électrophysiologie cardiaque
IHU-LIRYC, IMB - Institut de Mathématiques de Bordeaux, Inria Bordeaux - Sud-Ouest
Abstract : Since the 80's optical mapping has become an important tool for the study and the understanding of cardiac arythmias. This experiment allows the visualization of fluorescence fluxes through tissue surface. The fluorescence is directly related to the transmembrane potential. Information about its three-dimension distribution is hidden in the data on the surfaces. Our aim is to exploit this surface measurements to reconstruct the depolarization front in the thickness. For that purpose we developed a method based on the resolution of an inverse problem. The forward problem is made of two diffusion equations and the parametrization of the wavefront. The inverse problem resolution enables the identification of the front characteristics. The method has been tested on in silico data with different ways to parameter the front (expanding sphere, eikonal equation). The obtained results are very satisfying, and compared to a method derived by Khait et al. [1]. Moving to experimental data put in light an incoherence in the model. We detail the possible causes we explored to improve the model : constant illumination, optical parameters, accuracy of the diffusion approximation. Several inverse problems are considered in this manuscript, that involves several cost functions and associated gradients. For each case, the calculation of the gradient is explicit, often with the gradient method. The presented method was also applied on data other than cardiac optical mapping.
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Gwladys Ravon. Problèmes inverses pour la cartographie optique cardiaque. Analyse numérique [math.NA]. Université de Bordeaux, 2015. Français. ⟨NNT : 2015BORD0118⟩. ⟨tel-01251706v2⟩

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