Diffusion Magnetic Resonance Imaging of Central Nervous System Diseases: Structure, Function and Pathology
Date of Award
Doctor of Philosophy (PhD)
Diffusion magnetic resonance imaging (MRI) is a noninvasive imaging modality widely used to probe the microstructure of central nervous system (CNS). Studies have demonstrated that progression of the CNS pathology may increase or decrease apparent diffusion coefficient (ADC) measured by diffusion MRI, and the axial and radial diffusivities derived from diffusion tensor imaging (DTI) have shown promises to separate axonal injury from myelin damage. Recently, diffusion MRI was also used to predict functional outcome in various CNS diseases. In this dissertation, diffusion MRI was first employed to image the normal retinal cell structure. The retinal cell pathology of retina degeneration-1 (rd1) mice was then evaluated by diffusion MRI and found that the photoreceptor cell death induced retinal vascular leakage causes increased inner retinal ADC in living rd1 mice. To further investigate the unknown relationship between DTI-derived biomarkers of axonal injury and myelin damage and changes in functional behavior of white matter tracts, in vitro electrophysiological recordings of compound action potential (CAP) were conducted to evaluate the function of mouse optic nerves after transient retinal ischemia. The correlation between CAP measurements and DTI injury markers was established. In this dissertation, a novel diffusion MRI method, diffusion basis spectrum imaging (DBSI), was employed to detect and quantify neuroinflammation as well as coexisting axon/myelin damage in a single setting. Our findings suggest that diffusion MRI is a promising noninvasive tool in investigating the structure, function and pathology of CNS.
Philip V Bayly
Dennis L Barbour, Anne H Cross, Guy M Genin