High resolution quantitative imaging of multiple sclerosis at 7 Tesla

This thesis investigates the normal appearing brain tissue in multiple sclerosis (MS) using high resolution quantitative MRI measures acquired at high magnetic field. The use of magnetisation transfer ratio (MTR) and longitudinal time (T1) were employed to investigate changes in normal appearing white matter (NAWM) for healthy control subjects and patients with clinically isolated syndromes suggestive of MS (CIS) and relapsing-remitting multiple sclerosis (RRMS). The results showed a significant difference in the median peak position, full width at half maximum, the 25th percentile of the MTR histograms and the 75th of the T1 histograms. The magnetic susceptibility mapping technique was used to quantitatively investigate the accumulation of iron in deep grey matter structures in healthy controls, CIS and RRMS patients. The results showed an increase in iron deposition in the caudate nucleus, putamen, globus pallidus structure in CIS and RRMS when compared to those in healthy controls. Combining functional MRI and magnetic susceptibility mapping was used to elucidate the mechanisms underlying the visual activation in lateral geniculate nucleus (LGN) in healthy controls. The results showed an increase in the accuracy of the LGN delineation. This is in turn, highlights the importance of this method in quantifying the visual disturbances associated with MS and CIS patients.EThOS - Electronic Theses Online ServiceGBUnited Kingdo