Imaging diagnosis of small hepatocellular carcinoma.

To elucidate the detectability of small hepatocellular carcinoma by various imaging modalities, we performed digital subtraction angiography, computed tomographic arterioportography and carbon dioxide-enhanced ultrasonography. Of 76 patients with a small hepatocellular carcinoma of 2 cm or less in maximum diameter, 61 underwent digital subtraction angiography, computed tomographic arterioportography and enhanced ultrasonography at the same time. Concerning the 61 patients undergoing all the procedures, the characteristics of hepatocellular carcinoma were found in 57.4% (35 of 61) by digital subtraction angiography, 75.4% (46 of 61) by computed tomographic arterioportography and 72.1% (44 of 61) by enhanced ultrasonography. Among them, four hepatocellular carcinomas were detected only by enhanced ultrasonography, three were diagnosed only by computed tomographic arterioportography and two were diagnosed by both of them. Except for six hemangioma nodules that were easily diagnosed only with angiography, four of 55 benign hepatic nodules (7.3%) showed false-positive findings suggestive of hepatocellular carcinoma with either computed tomographic arterioportography or enhanced ultrasonography. In conclusion, computed tomographic arterioportography and enhanced ultrasonography could complementarily detect a small hepatocellular carcinoma more sensitively than digital subtraction angiography.