Using triphasic helical CT to detect focal hepatic lesions in patients with neoplasms

OBJECTIVE. Our purpose was to determine the value of triphasic helical CT (unenhanced, hepatic arterial, and portal venous phases) in the detection and characterization of focal hepatic lesions due to hepatomas or metastases. MATERIALS AND METHODS. One hundred two patients with known or suspected hepatomas or liver metastases underwent triphasic CT. The number and conspicuity of lesions were evaluated on each phase. RESULTS. Five hundred eighty-four lesions were detected in 102 patients. Patients with hypovascular malignancies had more lesions detected on the portal venous phase with increased conspicuity than on the other phases. Patients with hypervascular malignancies had lesions best detected on the hepatic arterial phase, which revealed small lesions that were not seen on the other phases in seven (21%) of the 33 patients with hypervascular metastases and hepatomas. No lesions were detected on the unenhanced phase that were not seen on the other phases. However, arterial phase images introduced new diagnostic dilemmas because not all lesions seen on the arterial phase alone were caused by hepatomas or metastases, even in patients with known malignancies; several lesions represented benign abnormalities that included focal nodular hyperplasia. CONCLUSION. The unenhanced phase is not routinely necessary for the detection of metastases or hepatomas. Hypovascular malignancies are best evaluated during the portal venous phase. Small lesions due to hypervascular metastases and hepatomas are best evaluated and may be detected only during the hepatic arterial phase, which should be used routinely in these patients. New dilemmas may develop from the increased sensitivity of the hepatic arterial phase for lesions. However, the hepatic arterial phase is of limited value with hypovascular malignancies.