MRI: brain, orbits with gadolinium contrast! -95%, gadolinium enhancement persists 30d, short tau inversion recovery STIR, fast spin echo FSE, fluid-attenuated inversion recovery FLAIR, diffusion tensor imaging DTI, signal abnormalities can persist after recovery, may be present in MS patients without history of optic neuritis. Brain: ovoid, periventricular, >3mm white matter lesions. Spinal cord - low yield in selected patients