CHARACTERIZATION OF MRI RESPONSE TO TREATMENT WITH INTERFERON BETA-1B- CONTRAST-ENHANCING MRI LESION FREQUENCY AS A PRIMARY OUTCOME MEASURE

MRI is a valuable tool to examine the pathophysiology and natural hist ory of multiple sclerosis (MS), and several large multicenter trials h ave utilized MRI as a secondary outcome measure. We previously examine d the effect of interferon beta-1b on contrast-enhancing lesions on MR I using a baseline versus treatment design, and found that on treatmen t there is a reduction in mean frequency of enhancing lesions over the group. Using an expanded number of patients and the same trial design , we examined the individual response to treatment more extensively. W e find that the effect seen previously is still present, and that ther e is heterogeneity in the amount of decrease in contrast-enhancing les ions. This expanded number of patients and trial design allows for the discussion of new criteria for individual response to treatment, whic h are applied in the current trial. These approaches may be useful in the examination, early testing, and comparison of experimental therape utic agents in MS as well as in the characterization of patients who d o or do not have a response seen on MRI.