1. Noichi Central Hospital, Konan, Kochi, Japan.
2. Department of Surgery, Kochi Medical School, Nankoku, Kochi, Japan.
3. Department of Hepato-Biliary-Pancreatic Surgery, National Center for Global Health and Medicine, Tokyo, Japan.
4. Department of Hepato-Biliary-Pancreatic Surgery, Kyorin University Hospital, Mitaka, Tokyo, Japan.