1. From the Mellen Center for Multiple Sclerosis Treatment and Research (L.A.R., A.K.C., D.S.C., J.A.C., A.K.) and Diagnostic Radiology (J.L.), Cleveland Clinic, OH; Department of Neurosciences (J.G.), University of California San Diego, La Jolla, CA; UCSF Weill Institute of Neurosciences (S.S.Z.), University of California at San Francisco; and Department of Neurology (S.D.N.), Johns Hopkins School of Medicine, Baltimore, MD.