Serial contrast‐enhanced magnetic resonance imaging in patients with early relapsing–remitting multiple sclerosis: Implications for treatment trials

Serial monthly contrast‐enhanced MRIs were performed in 10 early relapsing–remitting patients with multiple sclerosis and 2 patients with chronic progressive disease for a period of 12 to 55 months. MRI was performed at 1.5 T using contiguous 5‐mm slices with pre‐ and postgadolinium‐diethylenetriamine pentaacetic acid (Gd‐DTPA) T1‐weighted and T2‐weighted images. New and total number of Gd‐DTPA‐enhancing lesions were numbered and counted and lesion areas were correlated to an increase of ≥:0.5 in Expanded Disability Status Scale (EDSS) scores. The frequency of enhancing lesions varied from patient to patient; however, there was correlation between a burst of enhancing lesion number and area above the individual's mean lesion frequency to an increase in EDSS score. A bootstrap analysis of the lesion count was performed to develop a statistical basis for determining population sizes for treatment trials. These results provide a basis for the potential use of contrast‐enhanced MRI as a primary outcome measure in phase II treatment trials involving patients with relapsing–remitting MS.