1. Department of Anesthesiology, Graduate School of Medicine, Chiba University, Chiba, Japan
2. Department of Anesthesiology, Chiba University Hospital, Chiba University, Chiba, Japan
3. Department of Radiology, Chiba University Hospital, Chiba University, Chiba, Japan
4. Department of Global Clinical Research, Graduate School of Medicine, Chiba University, Chiba, Japan