Prospective, blinded comparison of helical CT and CT arterial portography in the assessment of hepatic metastasis from colorectal carcinoma.
OBJECTIVE: This prospective blinded comparison of helical CT and helical CT arterial portography aimed to detect liver metastasis from colorectal carcinoma. METHODS AND MATERIALS: 50 patients with colorectal carcinoma were evaluated comparing helical CT with helical CT arterial portography. Each imaging study was evaluated on a 5-point ROC scale by radiologists blinded to the other imaging findings, and the results were compared, with the surgical and pathologic findings as the gold standard. RESULTS: Of the 127 lesions found at pathology identified as metastatic colorectal cancer, helical CT correctly identified 85 (69%) and CT portography 96 (76%). When subgroups with lesions <3 cm (48 patients) and patients with maximum tumor size <3 cm (18 patients) were considered, CT portography was always better than helical CT in terms of sensitivity, specificity, positive predictive value, and negative predictive value. ROC analysis adjusting for multiple lesions per patient revealed significantly greater area under the curve (AUC) for the subgroup of lesions <3 cm (CT-AUC of 77% and CT portography AUC of 81%; P = 0.002). CONCLUSIONS: For identification of large metastases, helical CT and CT portography have similar yield. However, for detection of small liver metastases, CT portography remains superior for lesion detectability.