Evaluation of Brain Atrophy in CIS Patients on Avonex

* Multiple sclerosis (MS) is a chronic inflammatory disorder characterized by focal areas of demyelination in the central nervous system (CNS). MRI findings suggest that we should look at gray matter atrophy as a marker of the disease process in MS. * Avonex is a proven effective disease-modifying treatment, which reduces total brain and GM atrophy and should be considered first-line therapy in patients with RRMS and CIS. * The original SET study is an open-label observational study of high risk subjects after CIS for development of CDMS that will enroll 220 patients who have started Avonex immediately after their first clinical attack in Czech Republic, and are followed with clinical and MRI examinations for 4 years at 0, 6, 12, 24, 36 and 48 months. The clinical and MRI acquisition examinations of this study are conducted in Czech Republic.