Longitudinal MRI in multiple sclerosis: correlation between disability and lesion burden.

We followed 18 multiple sclerosis patients clinically and with repeated brain MRIs with and without gadolinium for over 1 year. Clinical evaluations included scoring on the Kurtzke Expanded Disability Status Scale (EDSS) and the Ambulation Index (AI) scale. There was a significant correlation between the change in EDSS or AI and the change in number of lesions on MRI and between cumulative number of lesions on MRI and cumulative change in EDSS or AI. Our findings support the validity of MRI as a measure of clinical activity and potentially as an objective quantitative outcome measure for assessing response to therapy.