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Magnetic Resonance Imaging Of Brain Tissue Abnormalities: Transverse Relaxation Time In Autism And Tourette Syndrome And Development Of A Novel Whole-Brain Myelin Mapping Technique, Yann Gagnon

Electronic Thesis and Dissertation Repository

The transverse relaxation time (T2) is a fundamental parameter of magnetic resonance imaging sensitive to tissue microstructure and water content, thus offering a non-invasive approach to evaluate abnormalities of brain tissue in-vivo. Prevailing hypotheses of two childhood psychiatric disorders were tested using quantitative T2 imaging and automated region of interest (ROI) analyses. In autism, the under-connectivity theory, which proposes aberrant connectivity within white matter (WM) was assessed, finding T2 to be eleveted in the frontal and parietal lobes, while dividing whole brain data into neurodevelopmentally relevant WM ROIs found increased T2 in bridging and radiate WM. In Tourette syndrome, tissue …