1. Department of Organ Transplantation, Gastroenterological and Hepatobiliary Surgery, Graduate School of Comprehensive Human Sciences; University of Tsukuba; 1-1-1 Tennodai Tsukuba 305-8575 Japan
2. Department of Radiology; Mitsui Memorial Hospital; 1 Kandaizumityo, Tiyodaku Tokyo 101-8643 Japan