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

Abstract

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. 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. 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. 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.