1. Department of Radiology, Seoul National University College of Medicine, Seoul, South Korea
2. Department of Radiology, Keimyung University Dongsan Medical Center, Daegu, South Korea
3. Department of Radiology, Korea University Anam Hospital, Seoul, South Korea
4. Department of Neurosurgery, Seoul National University College of Medicine, Seoul, South Korea
5. Department of Radiology, Seoul National University College of Medicine; Clinical Research Institute, Seoul National University Hospital; and Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, South Korea