1. Department of Endovascular Neurosurgery, Toranomon Hospital, Tokyo, Japan
2. Department of Radiological Technology, Toranomon Hospital, Tokyo, Japan
3. Department of Neurosurgery, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
4. Division of Stroke Prevention and Treatment, Department of Neurosurgery, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan