1. Departments of Neurosurgery, Ishinkai Yao General Hospital, Yao, Osaka, Japan
2. Departments of Radiology and Interventional Radiology, Ishinkai Yao General Hospital, Yao, Osaka, Japan
3. Department of Radiology, Nara Medical University, Kashihara, Nara, Japan
4. Department of Neurosurgery, Nara Medical University, Kashihara, Nara, Japan