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Traitement et simulation d’images d’IRM de perfusion pour la prédiction de l’évolution de la lésion ischémique dans l’accident vasculaire cérébral

Mathilde Giacalone 1, 2
2 Images et Modèles
CREATIS - Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé
Abstract : Stroke – a neurological deficit resulting from blood supply perturbations in the brain – is a major public health issue, representing the third cause of death in industrialized countries. There is a need to improve the identification of patients eligible to the different therapies, as well as the evaluation of the benefit-risk ratio for the patients. In this context, perfusion Dynamic Susceptibility Contrast (DSC)-MRI, a prominent imaging modality for the assessment of cerebral perfusion, can help to identify the tissues at risk of infarction from the benign oligaemia. However, the entire pipeline from the acquisition to the analysis and interpretation of a DSC-MRI remains complex and some limitations are still to be overcome. During this PhD work, we contribute to improving the DSC-MRI processing pipeline with the ultimate objective of ameliorating the prediction of the ischemic lesion evolution in stroke. In a first part, we primarily work on the step of temporal signal deconvolution, one of the steps key to the improvement of DSC-MRI. This step consists in the resolution of an inverse ill-posed problem and allows the computation of hemodynamic parameters which are important biomarkers for tissue fate classification in stroke. In order to compare objectively the performances of existing deconvolution algorithms and to validate new ones, it is necessary to have access to information on the ground truth after deconvolution. To this end, we developed a numerical simulator of DSC MRI with automatically generated ground truth. This simulator is used to demonstrate the feasability of a full automation of regularization parameters tuning and to establish the robustness of a recent deconvolution algorithm with spatio-temporal regularization. We then propose a new globally convergent deconvolution algorithm. Then, this first part ends with a discussion on another processing step in the DSC-MRI pipeline, the normalisation of the hemodynamic parameters maps extracted from the deconvolved images. In a second part, we work on the prediction of the evolution of the tissue state from longitudinal MRI data. We first demonstrate the interest of modeling longitudinal MRI studies in stroke as a communication channel where information theory provides useful tools to identify the hemodynamic parameters maps carrying the highest predictive information, determine the spatial observation scales providing the optimal predictivity for tissue classification as well as estimate the impact of noise in prediction studies. We then demonstrate the interest of injecting shape descriptors of the ischemic lesion in acute stage in a linear regression model for the prediction of the final infarct volume. We finally propose a classifier of tissue fate based on local binary pattern for the encoding of the spatio-temporal evolution of the perfusion MRI signals
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Submitted on : Friday, January 12, 2018 - 4:38:08 PM
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  • HAL Id : tel-01683014, version 1


Mathilde Giacalone. Traitement et simulation d’images d’IRM de perfusion pour la prédiction de l’évolution de la lésion ischémique dans l’accident vasculaire cérébral. Imagerie médicale. Université de Lyon, 2017. Français. ⟨NNT : 2017LYSE1194⟩. ⟨tel-01683014⟩



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