Differential diagnosis of periampullary carcinomas: comparison of CT with negative-contrast CT cholangiopancreatography versus MRI with MR cholangiopancreatography.

Background: Negative-contrast CT cholangiopancreatography (nCTCP) has been introduced into clinical practice recently. In the present study, we compared CT with nCTCP vs. MRI with MR cholangiopancreatography (MRCP) for the differential diagnosis of periampullary carcinomas.

Methods: Fifty-nine patients with pathologically proven periampullary carcinomas who had received both CT and MR examinations before operation were reviewed retrospectively. Two reviewers independently interpreted the two image sets [the two-dimensional (2D)-CT with nCTCP set (CT set) vs. the 2D-MRI with MRCP set (MRI set)] in differentiating periampullary carcinomas, and the results were compared to the final pathologic records.

Results: An interobserver agreement with a weighed κ value of 0.868 for the CT set and 0.701 for the MRI set was obtained for both reviewers in this study. No statistically significant differences were observed in the accuracy of identifying each of the periampullary carcinomas of four origins (P values of 0.250, 0.500, 0.500, and 1.000 for reviewer 1 in comparison with 1.000, 0.625, 0.687, and 1.000 for reviewer 2 on the two image sets, respectively).

Conclusion: The CT set provides a comparable performance to that of the MRI set in differentiating periampullary carcinomas, and it may be an alternative to 2D-MRI with MRCP in assessing malignant biliary obstruction in patients who are not suitable for MR examinations.