Figure 1. Magnetic resonance imaging (MRI), magnetic resonance cholangiopancreatography (MRCP), and endoscopic retrograde cholangiopancreatography (ERCP) on admission (before treatment). (A) MRI and MRCP with contrast medium before treatment show multifocal strictures, partly dilated intrahepatic biliary tracts, and a central T2-signal-sparing lesion in the common bile duct (CBD). Those findings are usually indistinguishable from those of primary sclerosing cholangitis or hilar cholangiocarcinoma. There were no intrahepatic or pancreatic masses that could have caused an obstructive jaundice. In the contrast-enhanced, T1-weighted studies, no signs of pathological signal alterations were detectable in the pancreatic head. (B) ERCP on admission shows signs of intrahepatic and extrahepatic biliary tree dilatation and a subhepatic contrast medium-sparing lesion in the CBD. (C) Axial T1-weighted, contrast-enhanced MRI in a more delayed phase demonstrates a delayed enhancement of the pancreatic tail (arrow) compared to the pancreatic head (star). This is a characteristic feature of autoimmune pancreatitis. (D) Axial T2-weighted imaging reveals a slight but diffuse enlargement of the pancreatic tail and loss of normal fatty lobulation of the organ, along with a slim, hypointense halo around the pancreatic tail (arrow) compared to the head (star). The main pancreatic duct is tender and not dilated.