1. Department of Radiology, St.Vincent's Hospital, The Catholic University of Korea; Suwon, Korea
2. Department of Diagnostic Radiology, Bundang CHA Hospital, CHA University College of Medicine; Seongnam, Korea
3. Department of Neurosurgery, St.Vincent's Hospital, The Catholic University of Korea; Suwon, Korea
4. Department of Neurosurgery, Bundang CHA Hospital, CHA University College of Medicine; Seongnam, Korea