1. Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
2. Department of Radiology, Teikyo University School of Medicine, Tokyo, Japan.
3. Department of Surgery, Hepato-Biliary-Pancreatic Surgery Division, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
4. Department of Digestive Surgery, Hepatobiliary-Pancreatic Surgery Division, Toranomon Hospital, Tokyo, Japan.
5. Department of Pathology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.