1. Department of Neurosurgery, Seoul National University Bundang Hospital, Gyeonggi-do, Korea;
2. Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Korea;
3. Cerebrovascular Center, Pohang Stroke and Spine Hospital, Pohang, Korea;
4. Medical Research Collaborating Center and
5. Department of Radiology, Seoul National University Bundang Hospital, Gyeonggi-do, Korea