Benign and malignant nodules in cirrhotic livers: distinction based on blood supply. The blood supplies of nodular lesions associated with liver cirrhosis were analyzed in vivo with various imaging modalities. The portal blood supply was evaluated with computed tomography (CT) during arterial portography (CTAP); the arterial blood supply was evaluated with hepatic angiography, CT angiography, CT following intraarterial injection of iodized oil, or ultrasound following intraarterial injection of carbon dioxide microbubbles. A total of 84 surgically confirmed hepatocellular carcinomas (HCCs) (less than or equal to 3 cm) and 25 areas of adenomatous hyperplasia (AH) were included in the study. At CTAP, a portal blood supply was seen in 96% of cases of AH and only 6% of HCCs (chi 2, P less than .005). In contrast, an arterial supply greater than that of the surrounding liver was verified in 94% of the HCCs and only 4% of the cases of AH (chi 2, P less than .005). The blood supply of areas of AH with atypical hepatocytes and the blood supply of well-differentiated HCCs (Edmondson grade 1) tended to be intermediate between that of AH without atypia and that of HCC that was Edmondson and Steiner grade 2 or greater. Evaluation of the blood supply of the nodular lesions associated with liver cirrhosis is considered to be useful in the differential diagnosis and treatment of early-stage HCC. 