High-attenuation recent thrombus of the portal vein: CT demonstration and clinical significance.

Attenuation characteristics of portal vein thrombi on nonenhanced computed tomographic (CT) scans were assessed in 122 patients with proved portal vein thrombosis. Portal vein thrombi of high attenuation were found in four patients with hepatocellular carcinoma. From pathologic and radiologic studies, it was concluded that the high attenuation was caused by blood clots of recent onset formed at the tip of tumor thrombus. Differentiation from choledocholithiasis, hematobilia, and calcification of thrombi could be easily made by means of ultrasonography (US). Although plain CT is usually considered noncontributory in the diagnosis of venous thrombosis, it enabled the differentiation of recent thrombus in these four patients. Tumor thrombus in the major branches or main trunk of the portal vein is indicative of poor prognosis. When hepatic mass and high-attenuation portal vein thrombi are demonstrated with plain CT and substantiated by US, enhanced CT and angiography may be unnecessary for treatment of patients with advanced hepatocellular carcinoma.