1. Department of Neurosurgery, Guro Teun Teun Hospital, Seoul, Korea.
2. Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Korea.
3. Department of Neurosurgery, Inha University College of Medicine, Incheon, Korea.
4. Department of Radiology, Inha University College of Medicine, Incheon, Korea.