Benign diseases of the biliary ducts

Abstract

Accurate imaging diagnosis of biliary disease begins with knowledge of the normal appearance of the biliary tract. Non-diseased bile ducts are slender and regular in appearance when opacified with contrast material, such as by endoscopic retrograde cholangiography. At ultrasound and conventional CT, the intrahepatic bile ducts are either not visible, or are barely perceptible as tubular structures that, for the most part, parallel the portal veins. The left and right bile ducts and the second-order branches are most likely to be seen, but it is unusual to clearly see third-order or smaller branches of the biliary tract, even at MRCP. The extrahepatic bile duct is a thin tubular structure that normally does not exceed 7 mm in diameter. At CT and MRI, the wall of the intrahepatic and extrahepatic bile ducts should not be perceptible. The intra- and extrahepatic bile ducts may be slightly larger in diameter and more conspicuous in patients who have had prior cholecystectomy. No filling defects should be seen in the visible bile ducts.