The portal venous tree simulating dilated biliary ducts on computed tomography of the liver.

Intrahepatic portal veins may be identified on routine computed tomography (CT) of the liver. These venous structures appear as linear and branching, low-density regions in the liver which appear to converge at the porta hepatis. Intrahepatic portal veins may simulate the appearance of dilated intrahepatic bile ducts. Venous structures may be distinguished from dilated bile ducts by their obliteration following intravenous infusion of urographic contrast agents. CT numbers of portal veins tend to be somewhat higher than those of dilated bile ducts, but enough overlap of values exists to make reliance upon these numbers in an individual case suspect.