Figures 21, 22. (21) Left portal vein thrombosis secondary to ductal cholangiocarcinoma. Axial color Doppler US scan through the porta hepatis shows complete thrombosis of the left main and ascending branches (AP) of the portal vein from adjacent tumor invasion. Patent prominent hepatic arterial branches (yellow) run parallel to the thrombosed portal vein. Blue area indicates flow in the main portal vein. No flow is seen in the ascending left portal vein. bd = bile duct. (22) Hepatic artery encasement. Color Doppler US scan through the hepatoduodenal ligaments shows complete encasement of the proximal right lobar branch of the hepatic artery by a tumor mass. ha = hepatic artery, P = portal vein.