Ricardo Coronado Leija, D. Sc.
New York University

Quantifying white matter microstructure with diffusion MRI

Summary: In this talk, we will highlight the importance of biophysical modeling of the diffusion MRI signal in order to obtain metrics that are sensitive and specific to brain microstructure, with the focus on the Standard Model (SM) of diffusion in white matter, its validation, parameter estimation and clinical applications. We will discuss several approaches aimed at resolving the degeneracy issue commonly encountered in parameter estimation using clinically feasible dMRI protocols, and compare the model constraints of existing methods and an unconstrained, data-driven approach. We will present comprehensive histological validation of the SM parameters, in which WM microstructure in sham and injured rat brains was characterized using 3d electron microscopy and ex vivo dMRI. This validation reveals that SM is sensitive and specific to microscopic properties. We will also discuss application for human in vivo data regarding early development, multiple sclerosis and stroke. Finally, we will show how adding orthogonal measurements can help to estimate SM parameters more accurately.