Altered flow dynamics of intravascular contrast material to the liver in superior vena cava syndrome: CT findings

Background: To evaluate the findings of altered how dynamics in the livers of patients with obstruction of superior vena cava (SVC) on helical compute d tomography (CT). Methods: In six patients (age range = 28-80 years) with SVC obstruction, CT findings were retrospectively reviewed to identify the abnormal enhancemen t patterns of the liver and the relation with the extrahepatic collateral v essels and hepatic vessels. Results: Abnormal hepatic enhancement was observed in the following four (A -D) portions: (A) anterior portion of segment IV (n = 5), (B) subdiaphragma tic portion of the liver (n = 4), (C) posterior portion of the right lobe ( bare area; n = 1), and (D) lateral segment of the left lobe (n = 2). Two ma jor collateral pathways to the liver were demonstrated as follows: A and D --> from the umbilical vein to the left portal vein, and B and C --> from t he subcapsular vein to the bare area of the liver or to the hepatic veins. On helical CT, these collateral pathways were also clearly visualized. Conclusion: When these abnormal enhancements of the river on CT are recogni zed within the liver, these findings indicate diversion of contrast materia l into collateral pathways to the liver with SVC obstruction.