1Clinical Neuroscience, University of Cambridge, Cambridge, United Kingdom, 2Neurosurgery, Chang Gung Memorial Hospital, Keelung, Taiwan, 3Department of neurosurgery, Chang Gung University College of Medicine, Taoyuan, Taiwan, 4Department of radiology (EB44), University Medical Centre Groningen, Groningen, Netherlands, 5Department of radiology, University of Cambridge, Cambridge, United Kingdom, 6Brain tumour imaging laboratory, University of Cambridge, Cambridge, United Kingdom