<正>Objective: To investigate the imaging features and clinical significance of carbon dioxide digital subtraction angiography （CO2-DSA） in the diagnosis and treatment of hepatocellular carcinoma （HCC）. Methods: Both CO2-DSA and conventional DSA were performed in all 47 patients with HCC

and the angio-graphic manifestations of CO2-DSA were compared with those of conventional DSA in the same patients. Results: Peripheral arterial and capillary imaging by CO2-DSA was inferior to that by conventional DSA

although blood pools were well visualized with CO2. Improved visualization of arterioportal shunting （APS） was obtained with CO2-DSA compared with that by conventional angiography. APS was observed in 33 cases by CO2-DSA and in 12 cases by conventional angiography （P<0. 001）. Retrograde visualization of the portal vein （PV） trunk and its large branches was demonstrated in 16 cases by CO2-DSA and in 1 case by conventional DSA （P<0. 001）. The manifestation of lipiodol retention in the tumors was consistent with