Diffusion Magnetic Resonance Imaging in a Rat Hippocampal Slice Model of Acute Brain Injury

of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy DIFFUSION MAGNETIC RESONANCE IMAGING IN A RAT HIPPOCAMPAL SLICE MODEL OF ACUTE BRAIN INJURY By Timothy Michael Shepherd May 2003 Chair: Edward D. Wirth, III Major Department: Neuroscience This dissertation describes experiments using rat hippocampal slices as a model of nervous tissue to evaluate the changes in diffusion-weighted magnetic resonance images (MRI) observed after acute brain injury. A multislice perfusion chamber was designed to acquire diffusion-weighted MRI from multiple rat hippocampal slices simultaneously. These images had signal-to-noise ratios sufficient to analyze the multicomponent diffusion properties of water in rat hippocampal slices. Because the hippocampal slice water diffusion parameters were stable for at least 8 hours after procurement in this chamber, it enabled studies of the temporal evolution of diffusion changes in slices following perturbation with the calcium ionophore A23187. The mean fast diffusing water fraction (Ffast) progressively decreased for slices treated with 10 μM A23187 (-20.9 ± 6.3% at 8 hours). Slices treated with 50 μM A23187 had significantly reduced Ffast 80 minutes earlier than slices treated with 10 μM A23187 (P < 0.05). These data suggested diffusion-weighted images at high b-values and the diffusion parameter Ffast may be