Multiphasic helical CT in diagnosis and staging of hilar cholangiocarcinoma.

Abstract

The purpose of our study was to assess the potential of thin-section multiphasic helical CT in diagnosis and staging of hilar cholangiocarcinomas. Identically collimated helical CT studies were performed before and during the hepatic artery dominant phase and during the portal vein dominant phase of contrast enhancement in 29 consecutive patients with proven hilar cholangiocarcinomas. Differences in attenuation between the tumor and the liver were calculated in each case by subtracting the average attenuation of the tumor from that of the liver. A four-point scale termed a "lesion conspicuity score" was used to determine rates of tumor detection. CT findings were correlated with surgically assessed extent of tumor, histologic findings, or both in all cases. Ten (34%) of the 29 hilar cholangiocarcinomas were detected on unenhanced images. All hilar cholangiocarcinomas (100%) were seen on hepatic artery dominant phase scans, and 25 (86%) of 29 hilar cholangiocarcinomas were seen on portal vein dominant phase scans, regardless of the morphologic appearance. An infiltrating stenotic lesion was found in 17 (59%) of 29 patients, an exophytic hilar lesion was found in 11 patients (38%), and one patient (3%) had an intraluminal polypoid lesion. Mean differences in enhancement between infiltrating stenotic lesions and the liver were significantly greater on hepatic artery dominant phase scans (28 +/- 10 H) than on portal vein dominant phase scans (10 +/- 8 H), whereas the mean difference in enhancement between the exophytic lesions and the liver was statistically greater during the portal vein dominant phase (p < .01). Two of the hilar cholangiocarcinomas were resectable at surgery, and 18 were not. The overall accuracy of helical CT for assessing resectability was 60%. In 10 (56%) of 18 patients, unresectable disease was correctly diagnosed with helical CT (sensitivity, 56%). Eight (44%) of 18 patients considered to have resectable tumors with helical CT had unresectable tumors at surgery. A resectable tumor was correctly diagnosed in two patients with helical CT. Multiphasic helical CT can be used to detect and classify hilar cholangiocarcinomas. However, the exact proximal tumor extent along bile ducts tends to be underestimated with helical CT; therefore, helical CT is inaccurate for determining resectability.