Hepatocellular carcinoma and intrahepatic peripheral cholangiocarcinoma: enhancement patterns with quadruple phase helical CT--a comparative study.

PURPOSE: To define the hemodynamic features of hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma by using quadruple phase helical computed tomography (CT) and determine the value of this information in characterizing tumors. MATERIALS AND METHODS: Helical CT of the liver was performed in 45 patients with newly diagnosed HCC or peripheral cholangiocarcinoma. Scans were obtained before and 25 seconds, 70 seconds, and 2-6 minutes after the start of the contrast material injection. The intensity and spatial distribution of contrast material uptake were evaluated during all phases. Time-attenuation curves were established for each lesion. Relative attenuation and lesion conspicuity were assessed. A diagnostic confidence level was assigned to each lesion. RESULTS: In the majority of HCC lesions, a single, early peak of enhancement followed by a continuous decrease in tumor attenuation over time was seen. The greatest tumor conspicuity occurred during the delayed phase. In cholangiocarcinoma, tumor attenuation increased during the delayed phase. In the majority of lesions, the greatest tumor conspicuity was seen during the portal venous phase. In both tumor types, the diagnostic confidence level improved when the delayed phase was used. CONCLUSION: The variation over time in the intensity of contrast enhancement in HCC and cholangiocarcinoma differs sufficiently to make this a useful diagnostic criterion. The delayed phase is particularly important because it amplifies this difference.