1Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Beijing, China, People's Republic of, 2Department of Interventional Radiology, China Meitan General Hospital, Beijing, China, People's Republic of, 3State Key Laboratory of Brain and Cognitive Science, Beijing MR Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, People's Republic of, 4Department of Radiology, School of Medicine, University of Pennsylvania, Philadelphia, PA, United States, 5Department of Neurology, Peking Union Medical College Hospital, Peking Union Medical College, Beijing, China, People's Republic of