DO ARTERIAL PHASE HELICAL CT IMAGES IMPROVE DETECTION OR CHARACTERIZATION OF COLORECTAL LIVER METASTASES

Our goal was to determine if arterial phase images from dual phase hel ical CT improve either the detection or the characterization of hepati c metastases in patients with colorectal carcinoma. Sixty-two patients with known colorectal cancer underwent 65 dual phase helical CT exami nations to evaluate for possible liver metastases. Three blinded revie wers independently evaluated the portal venous phase images alone to d etermine ii hepatic metastases were present or absent. Arterial phase images were then analyzed to determine if they identified additional l esions or aided in characterizing small hepatic lesions. Scores of the two methods for diagnosing metastases were compared with the ''gold s tandard'' established by a consensus panel of three other radiologists who reviewed all images together with clinical, pathologic, and other imaging data. The addition of arterial phase imaging did not detect a ny new metastases. However, in 6 of the 64 technically adequate examin ations, hepatic arterial phase images increased lesion conspicuity and significantly increased diagnostic confidence when compared with port al vein phase scans alone. In patients with colorectal cancer, the add ition of arterial phase imaging does not increase sensitivity, but imp roves the specificity in diagnosing liver metastases in a small number of cases. Dual phase helical CT does not appear to be indicated in th e evaluation of liver metastases from colorectal cancer.