In vivo Microstructural MRI of healthy and diseased white matter

Can we obtain sub-millimeter information about tissue structure in vivo and non-invasively? In a diffusion MRI experiment, the signal encodes information about length scales of a few microns – much smaller than the actual MR image resolution of millimeters – and thus about features of the underlying tissue microstructure that lie in the mesoscale and that we otherwise cannot spatially resolve in vivo. The main challenge of the field is to decode this information and output specific and reliable biophysical parameters of tissue microstructure. In this talk, I will introduce the standard biophysical model for diffusion in white matter and explain its added value compared to e.g. Diffusion Tensor Imaging. I will then discuss its challenges, related to the topology of the fitting landscape which revealed multiple biologically plausible mathematical solutions, and I will show how this degeneracy was lifted and parameter specificity validated using clever experimental design in animal models. Finally, I will present applications of this tool to characterize white matter degeneration in the early stages of Alzheimer’s disease.
 
Bio
Ileana Jelescu is a research scientist within the EPFL core of the Center for Biomedical Imaging (CIBM). She received her PhD in Physics from Université Paris-Sud under the guidance of Denis Le Bihan and a double MSc in Engineering from Ecole Polytechnique and in Medical Physics from McGill University. She completed postdoctoral work at New York University School of Medicine on microstructural MRI of white matter using diffusion MRI and biophysical modeling. Her work now focuses on developing and validating evermore specific tools to characterize brain microstructure and function using diffusion and functional MRI, and understanding the interplay between microstructure and function in neurodegenerative diseases. She is the recipient of Jeanne Timmins Costello and Irtelis fellowships, and her original work as well as educational lectures have received multiple excellence awards from the International Society for Magnetic Resonance in Medicine, for which she currently serves as elected committee member.

Video transmission using zoom : https://epfl.zoom.us/j/9946495775