Radiologic manifestations of sclerosing cholangitis with emphasis on MR cholangiopancreatography

Magnetic resonance cholangiopancreatography (MRCP) is a relatively new, non invasive cholangiographic technique that is comparable with invasive endosc opic retrograde cholangiopancreatography (ERCP) in the detection and charac terization of extrahepatic bile duct abnormalities. The role of MRCP in eva luation of the intrahepatic bile ducts, especially in patients with primary or secondary sclerosing cholangitis, is under investigation. The key chola ngiographic features of primary sclerosing cholangitis are randomly distrib uted annular strictures out of proportion to upstream dilatation. As the fi brosing process worsens, strictures increase and the ducts become obliterat ed and the peripheral ducts cannot be visualized to the periphery of the li ver at ERCP. In addition, the acute angles formed with the central ducts be come more obtuse. With further progression, strictures of the central ducts prevent peripheral ductal opacification at ERCP. Cholangiocarcinoma occurs in 10%-15% of patients with primary sclerosing cholangitis; cholangiograph ic features that suggest cholangiocarcinoma include irregular high-grade du ctal narrowing with shouldered margins, rapid progression of strictures, ma rked ductal dilatation proximal to strictures, and polypoid lesions. Second ary sclerosing and nonsclerosing processes can mimic primary sclerosing cho langitis at cholangiography. These processes include ascending cholangitis, oriental cholangiohepatitis, acquired immunodeficiency syndrome-related ch olangitis, chemotherapy-induced cholangitis, ischemic cholangitis after liv er transplantation, eosinophilic cholangitis, and metastases.