Hepatic arterial and portal venous phase helical CT in patients treated with transcatheter arterial chemoembolization for hepatocellular carcinoma: Added value of unenhanced images

PURPOSE: To evaluate the additional diagnostic value of unenhanced computed tomographic (CT) images in the depiction of viable tumor in patients who were treated with transcatheter arterial chemoembolization (TACE) for hepatocellular carcinoma (HCC) and followed up with biphasic helical CT that included the acquisition of unenhanced images. MATERIALS AND METHODS: We performed helical CT (with unenhanced, arterial, and portal phases) in 54 patients who had been treated with TACE for HCC. Image analysis was first performed with only those images obtained in the arterial and portal venous phases of helical CT. A second analysis was then performed with unenhanced images, arterial images, and portal venous images that focused on the additional value of unenhanced images. The value of additional unenhanced images was evaluated by means of interobserver agreement (K statistic) and receiver operating characteristic (ROC) analysis. RESULTS: The two readers detected 128 and 129 lesions. Unenhanced images were valuable for 32 of 129 lesions (23 patients) for reader 1 and for 29 of 128 lesions (21 patients) for reader 2. Although there was no significant difference between biphasic CT alone and biphasic CT with unenhanced images, results of ROC analysis showed higher diagnostic performance with biphasic CT with unenhanced images than with biphasic CT alone for detecting viable tumor. CONCLUSION: The study data demonstrate the diagnostic value of unenhanced images interpreted in conjunction with biphasic CT images for follow-up of patients who have previously been treated with TACE for HCC. (C) RSNA, 2002.