Differential diagnosis of hepatic masses on computed tomography, with particular reference to hepatocellular carcinoma.

Differential diagnosis was attempted in 225 cases of hepatic masses using computed tomographic (CT) criteria. Hepatocellular carcinomas were suggested by the presence of an isodense mass, a narrow circular zone surrounding the mass, bulging of the tumor from the hepatic surface, decreased attenuation of an entire hepatic lobe, and diffuse homogeneous enhancement following bolus injection. The presence of liver cirrhosis on CT also favored the diagnosis of hepatocellular carcinoma. More than half the metastatic tumors showed findings rarely encountered in hepatocellular carcinomas, i.e., more than 10 lesions, masses with nodular margins and showing a gradual decrease in density toward the center, multiple calcifications, and peripheral enhancement following bolus injection. All cavernous hemangiomas were correctly diagnosed by serial scanning after bolus injections. Hepatic abscesses also revealed pathognomonic CT findings, while cholangiocarcinoma did not disclose characteristic features. Rapid serial scanning after the bolus injection of contrast medium was very helpful in the differential diagnosis of hepatic masses by CT.