Frederik Barkhof1, Peter S Pressman2. 1. From the UCL Institutes of Neurology and Healthcare Engineering (F.B.), London, UK; Department of Radiology & Nuclear Medicine (F.B.), Amsterdam University Medical Centers, the Netherlands; and Department of Neurology (P.S.P.), Behavioral Neurology Section, University of Colorado Anschutz Medical Center, Aurora. f.barkhof@vumc.nl. 2. From the UCL Institutes of Neurology and Healthcare Engineering (F.B.), London, UK; Department of Radiology & Nuclear Medicine (F.B.), Amsterdam University Medical Centers, the Netherlands; and Department of Neurology (P.S.P.), Behavioral Neurology Section, University of Colorado Anschutz Medical Center, Aurora.