Autoimmune pancreatitis: Multimodality non-invasive imaging diagnosis

Figure 1 Diffuse-type autoimmune pancreatitis. A-H: Computed tomography: the pancreas appears diffusely enlarged (arrows in A-D) with a hypodense peripancreatic rim, better visible in the venous phase (arrow in E). The lesion shows fair enhancement resulting almost isodense in the delayed phase (G-H). A plastic biliary endoprothesis is visible in the common bile duct (arrow in H); I-O: Magnetic resonance: the entire organ is slightly hypointense on T1-weighted images (arrow in I) and slightly hyperintense on T2-weighted images (arrow in J), with diffusion coefficient restriction (arrows in K and L) with intermediate-high b values. At dynamic examination the pancreatic lesion presents fair enhancement resulting almost isodense in the delayed phase (arrow in O).

Figure 2 Focal-type autoimmune pancreatitis. A-C: Computed tomography: the body of the pancreas appears focally enlarged (arrow in A) with a hypodense peripancreatic rim, better visible in the venous phase (arrow in B). The lesion shows fair enhancement resulting almost isodense in the delayed phase (arrow in C); D-K: Magnetic resonance: the affected portion of the pancreas is slightly hypointense on T1-weighted fat-saturated (arrow in D) images and slightly hyperintense on T2-weighted fat-saturated images (E), with diffusion coefficient restriction (arrows in F-G) with intermediate-high b values. At dynamic examination the pancreatic lesion shows fair enhancement resulting almost isodense in the delayed phase (arrow in J). At magnetic resonance cholangiopancr-eatography the main pancreatic duct shows a focal stenosis (long arrow in K) without upstream dilation. The intrahepatic bile ducts present irregular slightly stenotic portions (short arrows in K), due to involvement in the autoimmune process.