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Optimisation de l'IRMf BOLD pour l'étude de l'activation des ganglions de la base. : Application à la maladie de Parkinson.

Abstract : The basal ganglia (BG) are deep brain structures involved in the selection of appropriate behavior, with motor, cognitive and emotional components. The BOLD fMRI study of these structures is of great interest to explore their role and dysfunction in certain diseases, such as Parkinson's disease (PD). By studying the BOLD signal, this technique allows to identify brain activation following neuronal activation. However BOLD fMRI has been optimized for the study of cortical activations and detection of activations in the BG is difficult, mainly at the individual level. This is partly due to the fact that the BOLD signal is lower in these structures in relation to the cortex. Several reasons may explain the BOLD signal attenuation. Thereby, iron load in its structures, which changes the relaxation parameter T 2 *, may be a cause. Indeed, the BOLD signal is optimal when the echo time (TE) of the MRI acquisition sequence equal T 2 * of the considered brain structure. Our first work was to study the heterogeneity of T 2 * in different brain structures, taking into account the effects of PD. Indeed, PD is known to induce iron accumulation some regions. We also studied the evolution of T 2 * longitudinally, and this parameter has emerged as an interesting biomarker to track PD progression. The second work was to study the activation of BG taking into account T 2 * heterogeneity. We studied brain activation during a motor task, exploring in particular the effect of TE. We showed that the choice of TE has a low impact on BG activation detection sensitivity. We propose a strategy for individual quantification of neuronal activity in the BG, using the BOLD percentage signal change in pre-defined regions of interest, obtained from the group analysis.
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Submitted on : Monday, September 17, 2018 - 6:51:06 PM
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  • HAL Id : tel-01875807, version 1



Miguel Ulla. Optimisation de l'IRMf BOLD pour l'étude de l'activation des ganglions de la base. : Application à la maladie de Parkinson.. Médecine humaine et pathologie. Université d'Auvergne - Clermont-Ferrand I, 2013. Français. ⟨NNT : 2013CLF1MM07⟩. ⟨tel-01875807⟩



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