1. Department of Radiology, Seoul National University College of Medicine, Seoul, Korea
2. Department of Neurological Surgery, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania
3. Department of Neurosurgery, Jeju National University College of Medicine, Jeju, Korea
4. Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Korea
5. Departments of Radiology and Neurosurgery, 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, Korea