1 Department of Hepato-Biliary and Pancreatic Surgery, Okayama University Hospital, 2-5-1 Shikata-cho, Kita-ku, Okayama, 700-8558, Japan. Electronic address: kotakagi15@gmail.com.
2 Department of Hepato-Biliary and Pancreatic Surgery, Okayama University Hospital, 2-5-1 Shikata-cho, Kita-ku, Okayama, 700-8558, Japan.