Investigating and validating MRI-based markers of white matter microstructure. (360G-Wellcome-091509_Z_10_A)

Magnetic resonance imaging (MRI) offers remarkably flexible contrast (ability to discriminate between tissues) because it probes water, which exists in almost every tissue environment and is sensitive to local tissue structure. Taking advantage of the flexible contrast in MRI and prevalence of water in the brain, researchers have begun to propose techniques for measuring white matter microstructural properties such as myelination, iron content, axonal diameter and axonal density. The ultimate goal is to create a suite of MRI in vivo histology tools; however, these emergent methods remain at an early stage. I will develop novel measures of white matter microstructure in living humans: specifically, new approaches to susceptibility (Aim 1) and diffusion imaging (Aim 2). The first aim will explore recent advances in image contrast that are based on the tissue property of magnetic susceptibility. I will use Oxford s upcoming state-of-the-art 7-Tesla scanner and a method I recently deve loped to understand and exploit this contrast, which detects chemical species such as iron and myelin. The second aim will consider diffusion methods for measuring the geometric properties of white matter fibers, such as axonal diameter and density. I will develop novel acquisition techniques that are appropriate for use in living humans.