Affiliation: | 1. Department of Radiology, Singapore General Hospital, Block 4, Level 1, Outram Rd, Singapore 169608;2. Department of Radiology, Division of Neuroradiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA;3. Department of Radiology, B2 A209, University of Michigan Health System, 1500 E. Medical Center Drive, Ann Arbor, MI 48109-0030, USA |