Magnetization transfer ratio in gray matter: a potential surrogate marker for progression in early primary progressive multiple sclerosis.

BackgroundMagnetization transfer imaging has the potential to provide a surrogate marker for progression in primary progressive multiple sclerosis (PPMS).ObjectivesTo investigate whether brain magnetization transfer imaging, T2 lesion load, and atrophy changes over 3 years reflect concurrent clinical changes, and which baseline imaging measure best predicts progression over 3 years in early PPMS.DesignProspective study.SettingNational Hospital for Neurology and Neurosurgery and the Institute of Neurology, London, England.PatientsForty-seven patients with PPMS (of whom 43 completed the study) and 18 control subjects.InterventionsBrain magnetization transfer imaging (including T2-weighted images) and volume sequences every 6 months for 3 years.Main outcome measuresChanges in Expanded Disability Status Scale (EDSS) score and associations with rate of change in imaging variables.ResultsMore rapid decline in gray matter mean and peak location magnetization transfer ratio and T2 lesion load increase were associated with greater rates of progression on the EDSS. Baseline gray matter peak height magnetization transfer ratio best predicted progression over 3 years.ConclusionGray matter magnetization transfer ratio meets many of the criteria for a surrogate marker of progression in early PPMS