Fig. 2

Typical CT and MR imaging appearance of type 1 autoimmune pancreatitis. Axial pre-enhanced (a), arterial (b), venous (c) phase on CT images and axial T2WI (e), T1WI (f), pancreatic (g), portal venous (h) and delayed venous (i) phase on MR imaging showed diffuse pancreatic enlargement with homogenous enhancement (star sign). On MR imaging, it appeared hypointense during the pancratic phase (g) compared with the spleen, and became hyperintense during the portal venous phase (h) compared with the pancreatic phase (g) and isointense during the delayed venous phase (i) compared with the portal venous phase (h). Peripancreatic vessel stricture (straight white arrows) was observed on both CT and MR images (b, c, g, h and i). Extrapancreatic involvement including the common bile duct (curved white arrows on g, h and i) and kidney (straight black arrows on d and g) were noted. The MR cholangiopancreatography (j) showed the stricture of the common bile duct and the dilatation of the upstream extrahepatic duct (curved white arrow)