1. Department of Radiology, HITO Medical Center, Shikokuchuo, Ehime, Japan
2. Department of Neurovascular Medicine, HITO Medical Center, Shikokuchuo, Ehime, Japan
3. Department of Neurosurgery, HITO Medical Center, Shikokuchuo, Ehime, Japan
4. Department of Neurosurgery, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan