Fig. 3

The late phase of contrast-enhanced MRI; a Axial view. b Coronal view. The peripheral part of the lesion had a low signal, while its central part had a high signal. The lower bile duct and the main pancreatic duct were involved and obstructed by the central part of the lesion. However, the upper and middle bile duct, superior mesenteric vein, duodenum, and gall bladder were not involved by the peripheral part of the lesion. Ao aorta, CBD common bile duct, Du duodenum, GB gall bladder, SMA superior mesenteric artery, SMV superior mesenteric vein, PD pancreatic duct