Magnetization transfer imaging to monitor clinical trials in multiple sclerosis

Magnetization transfer imaging (MTI) is a sensitive magnetic resonance scan ning technique for detecting disease activity and monitoring disease progre ssion in multiple sclerosis (MS) patients. To date, MTI has not been used a s an outcome measure in early phase and pivotal clinical trials. Magnetizat ion transfer ratio, a quantitative measure of MT, can be used to follow the evolution of individual MS plaques as well as microscopic disease in norma l-appearing white matter (NAWM). Volumetric whole brain NIT ratios of every voxel in the brain can be expressed as a histogram, providing an estimate of cerebral atrophy and a global disease activity including "occult" diseas e in NAWM, thus providing a quantitative measure of a therapeutic response. This report will briefly focus on how MTI could be used to monitor a thera peutic response in a treatment trial and address some of the pitfalls/limit ations of MTI that can be encountered even in a well-designed longitudinal study.