1. Departments of Cerebrovascular Disease, Cerebrovascular Center and Clinical Research Institute, Kyushu Medical Center, National Hospital Organization, Chuo-ku, Fukuoka, Japan
2. Departments of Neuroradiology, Cerebrovascular Center and Clinical Research Institute, Kyushu Medical Center, National Hospital Organization, Chuo-ku, Fukuoka, Japan
3. Departments of Neurosurgery, Cerebrovascular Center and Clinical Research Institute, Kyushu Medical Center, National Hospital Organization, Chuo-ku, Fukuoka, Japan
4. Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.