Interferon beta treatment for multiple sclerosis has a graduated effect on MRI enhancing lesions according to their size and pathology

OBJECTIVE—The ability of recombinant human interferon β-1a (rh-IFN β-1a) to suppress multiple sclerosis activity, evaluated from MRI, was assessed across a range of lesions enhancing at different gadolinium-DTPA (Gd) doses and with different sizes. METHODS—Every 4 weeks, standard dose (Sd; 0.1 mmol/kg Gd) and triple dose (Td; 0.3 mmol/kgGd) MRI were obtained from 18 patients with relapsing-remitting multiple sclerosis for 3 months before and 4 months after starting treatment with 44 µg rh-IFN β-1a subcutaneously, once a week. RESULTS—The total numbers of enhancing lesions were 145 and 126 on Sd scans and 278 and 192 on the Td scans obtained before and after treatment. The introduction of treatment decreased, on average, the rate of appearance of new enhancing lesions seen on Sd and Td scans by 37% (p