Portal vein involvement in hepatocellular carcinoma: dynamic CT features.

The authors conducted a retrospective examination of 62 hepatocellular carcinomas, taking dynamic CT scans of selected sections after an intravenous contrast bolus. The proximal portal vein was involved in 40% of cases and the distal segment in 16%. Angiographic correlation was available in 23 patients. CT signs of main or lobar portal vein involvement included (a) hypodensity and enlargement, (b) periportal arterial hypervascularization surrounding the hypodense intraluminal region, (c) nonvisualization of the lobar portal vein, (d) arterioportal shunting, and (e) differences in lobar attenuation. The characteristic appearance of tumor within the portal vein was noted in many cases; in others, distinction between tumor and bland thrombus could not be made. Peripheral portal vein obstruction was suggested when a small, hypervascular tumor became hypodense during the portal phase of CT. The frequency and significance of these CT signs of portal vein involvement are discussed.