1. Center for Frontier Medical Engineering, Chiba University, Chiba, Japan.
2. Department of Urology, Teikyo University Chiba Medical Center, Ichihara, Japan.
3. Department of Anesthesiology, Teikyo University Chiba Medical Center, Ichihara, Japan.
4. Department of Anesthesiology, Graduate School of Medicine, Chiba University, Chiba, Japan.