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