Correlations between changes in disability and T2-weighted brain MRI activity in multiple sclerosis: a follow-up study.

We obtained two conventional unenhanced T2-weighted brain MRI scans, separated by an interval of 24 to 36 months, in 281 patients with multiple sclerosis (MS). At the time of each scan, clinical disability was rated using the Kurtzke Expanded Disability Status Scale (EDSS). Changes in disability between the two examinations correlated weakly but significantly with the number of new (Spearman's rank correlation coefficient = 0.13; p = 0.02) and enlarging (Spearman's rank correlation coefficient = 0.18; p = 0.002) MRI lesions. This result suggests that brain T2-weighted MRI is a useful supplementary marker of disease activity in definitive (phase III) clinical treatment trials in MS.