MR imaging in multiple sclerosis will show lesions in white matter with a periventricular predominance. In Multiple sclerosis, demyelinating plaques occur in the periventricular regions, corpus callosum, brainstem and cerebellum. Plaques are more periventricular, oval in shape, have irregular margins and are oriented perpendicular to ventricles. Ref: Magnetic Resonance in Multiple Sclerosis By David Hugh Miller, Page 33; The Neurobiology of Multiple Sclerosis By Alireza Minagar, Page 287; Harrison's Principles of Internal Medicine, 18th Edition, Chapter 380