1. Department of Radiology, Severance Stroke Center, Severance Hospital, Yonsei University College of Medicine, Seoul;
2. Department of Neurosurgery, Yonsei Gamma Knife Center, Severance Hospital, Yonsei University College of Medicine, Seoul; and
3. Department of Neurosurgery, Severance Stroke Center, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea