Magnetic resonance cholangiopancreatography (MRCP).The cystic duct and common bile duct are markedly distended with a smooth and short narrowing (solid arrow) at the distal aspect. No biliary stone is identified. The main pancreatic duct (dotted arrow) is not involved. Along the distal common duct, there is an area of ill-defined increased T2-weighted signal. The adjacent duodenal wall (*) shows prominently increased T2-weighted signal that reflects oedema which can be reactive to an infiltrative disease.