Alexandros Ferles1, Frederik Barkhof2. 1. Department of Radiology and Nuclear Medicine, Amsterdam University Medical Center, Vrije Universiteit, Amsterdam 1081 HV, Netherlands. 2. Department of Radiology and Nuclear Medicine, Amsterdam University Medical Center, Vrije Universiteit, Amsterdam 1081 HV, Netherlands; Queen Square Institute of Neurology and Centre for Medical Image Computing, University College London, London, UK. Electronic address: f.barkhof@amsterdamumc.nl.