1. Department of Radiology, Graduate School, Kyung Hee University, Seoul, Korea.
2. Department of Radiology, Kyung Hee University Hospital, Kyung Hee University School of Medicine, Seoul, Korea.
3. Department of Radiology, Kyung Hee University Hospital at Gangdong, Kyung Hee University School of Medicine, Seoul, Korea.
4. Department of Neurosurgery, Kyung Hee University Hospital, Kyung Hee University School of Medicine, Seoul, Korea.