Venous Invasion in Hepatocellular Carcinoma - CT

Hepatocellular carcinoma is characterized by its strong propensity for invasion of vascular structures, mainly the portal vein and, uncommonly, the hepatic veins and inferior vena cava (IVC). Differentiating malignant from bland thrombus is crucial in determining the therapeutic approach, as the presence of malignant venous invasion is considered an advanced stage with limited therapeutic options and poorer prognosis. Adequate triphasic computed tomography (CT) is important in the detection of macrovascular venous invasion and in assessing the extent of malignant thrombus. Features of malignant thrombus include expansion of the vein, enhancement, internal neovascularity, direct continuity with the HCC mass, and showing a similar pattern to that of HCC. The presence of large malignant thrombus can cause significant hemodynamic changes in the liver; also, large malignant portal venous thrombus (PVTT) can cause portal hypertension, gastrointestinal bleeding, and might lead to multiple intrahepatic tumor seeding and recurrence. Involvement of the inferior vena cava by tumor thrombus and the right atrium can lead to secondary Budd–Chiari syndrome, pulmonary embolism, pulmonary metastases, and immediate death if the malignant thrombus infiltrates the heart. Determining the extent of malignant thrombus is important in choosing the appropriate management, whether hepatic resection if the thrombus is limited or systemic therapy in advanced cases. Missing venous invasion has a great negative impact on patient management; causes of missing it include inadequate imaging, similar patterns of malignant thrombus to the primary tumor, forgetting to revise hepatic veins and IVC (which is not usually written in templates), and doctor exhaustion.