1. Department of Neurosurgery, Cerebrovascular Center, Gangnam Severance Hospital, Seoul, Korea.
2. Severance Institute for Vascular and Metabolic Research, Yonsei University College of Medicine, Seoul, Korea.
3. Department of Neurology, Cerebrovascular Center, Gangnam Severance Hospital, Seoul, Korea.
4. Department of Radiology, Cerebrovascular Center, Gangnam Severance Hospital, Seoul, Korea.