From the Danish Multiple Sclerosis Center (H.H.C., J.T., L.M., M.M., S.B., R.H.H., M.B., J.R.C., P.S.S., M.E., F.S.), Copenhagen University Hospital, Rigshospitalet Glostrup, Glostrup; Danish Research Centre for Magnetic Resonance (H.L., C.G.M., H.R.S.), Copenhagen University Hospital Hvidovre, Hvidovre; Section of Biostatistics (T.L.), Department of Public Health, University of Copenhagen, Copenhagen K; Department of Neurology (H.R.S.), Copenhagen University Hospital Bispebjerg, Copenhagen; and Institute for Clinical Medicine (H.R.S.), University of Copenhagen, Copenhagen N, Denmark.