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June 30- 14:00 Thesis defence - Nicolas Moutal

par Anne-Marie - publié le

Despite several qualities, magnetic resonance imaging (MRI) suffers from a poor spatial resolution ( 1mm). This prevents the observation of fine details and limits the range of usability of MRI, in particular in medical diagnosis. More than 60 years ago, it was discovered that a MRI scanner allows one to measure diffusive properties of tissues, i.e. the mobility of water inside the tissues. This information allows in principle to recover microstructural informations because : 1) the mobility of water is related to the structure of the sample (for instance, orientation of fibers, crowding, etc.) ; 2) the typical distance traveled by water molecules during an MRI acquisition is of the order of 5-50 µm.
Thus, the so-called diffusion MRI technique aims at measuring diffusive properties of tissues and deducing some informations at the micrometer scale. This indirect method raises numerous difficulties at the experimental, numerical, and mathematical level. During my thesis, we extended some previous results in the field. In particular, we focused on the often ignored ``localization regime’’, which could potentially enhance the sensitivity of measurements to the microstructure of samples.