Magnetization transfer magnetic resonance imaging and clinical changes in patients with relapsing-remitting multiple sclerosis

Background: Magnetization transfer (MT) magnetic resonance imaging (MRI) can provide in vivo quantitative estimates of microscopic tissue damage in normal-appearing white matter (NAWM) and gray matter (GM) from patients with multiple sclerosis (MS). Objective: To determine whether a onetime MT MRI can provide markers of short-term disease evolution in patients with relapsing-remitting MS. Design: Eighteen-month observational study. Setting: Neuroimaging Research Unit, Scientific Institute and University Ospedale San Raffaele. Patients: Twenty-two patients with untreated relapsing-remitting MS. Main Outcome Measures: Relapse rate; disability according to the Expanded Disability Status Scale (EDSS); dual-echo, 2-dimensional gradient echo with and without a saturationMTpulse and T1-weighted MRIs of the brain; and MT ratio (MTR) histograms for NAWM and GM. Results: During the study period, 13 patients (59%) experienced 25 relapses. The median EDSS score was 1.25 (range, 0-3.5) at study entry and 1.75 (range, 0-3) at study exit. Significant, although moderate, correlations were found between average GM MTR values at baseline and EDSS changes during the study period (r=-0.44; P=.04). A trend was observed for the correlation between NAWM MTR values at baseline and the EDSS changes throughout 18 months (r=-0.42; P=.05). For the relation between EDSS changes and baseline GM MTR, the slope of the regression line was -0.5 (95% confidence interval, -1.0 to 0.0), indicating that a decrease in the baseline GM MTR of 1% predicted an increase in the EDSS score of 0.5 point throughout the 18 months. Conclusion: This study indicates that a "snapshot" MT MRI assessment detects subtle brain tissue changes that are associated with short-term disability accumulation in patients with relapsing-remitting MS.