Evaluation of Perihilar Biliary Strictures: Does DWI Provide Additional Value to Conventional MRI?

Objective: The purpose of this study is to evaluate whether DWI provides additional value to conventional MRI with MRCP (MRI-MRCP) in the characterization of perihilar biliary strictures and in the evaluation of the longitudinal extent of perihilar cholangiocarcinomas.

Materials And Methods: One hundred fourteen patients with perihilar strictures (81 malignant and 33 benign) underwent gadobutrol-enhanced MRI-MRCP and DWI using 10 b values (0-1000 s/mm(2)). Two readers independently reviewed a conventional set of MRI-MRCP images and a combined set of MRI-MRCP and DW images and scored the likelihoods of malignancy for perihilar strictures and involvement of the bilateral secondary confluence in malignant cases on a 5-point scale. The diagnostic performance of the two imaging sets was compared using ROC analysis.

Results: In the characterization of 114 perihilar strictures, the addition of DWI showed no statistically significant improvement in diagnostic performance (reader 1, area under the ROC curve (Az) = 0.947 vs 0.923; reader 2, Az = 0.930 vs 0.905; all p > 0.05) with an interobserver agreement of κ = 0.763-0.818. In determining bilateral secondary confluence involvement for the 81 surgically confirmed malignant strictures, the conventional and combined sets showed no statistically significant difference in diagnostic performance (reader 1, Az = 0.820 vs 0.868; reader 2, Az = 0.826 vs 0.829; all p > 0.05), with κ = 0.564-0.588.

Conclusion: The addition of DWI to conventional MRI-MRCP did not improve diagnostic performance in the characterization of perihilar strictures or in determining whether the bilateral secondary biliary confluence was involved in perihilar cholangiocarcinomas.