Differential Diagnosis of Benign and Malignant Distal Biliary Strictures: Value of Adding Diffusion-Weighted Imaging to Conventional Magnetic Resonance Cholangiopancreatography

PurposeTo determine the value of adding diffusion-weighted imaging (DWI) to conventional magnetic resonance cholangiopancreatography (MRCP) for differentiating benign from malignant distal biliary strictures. Materials and MethodsTwo independent readers reviewed three image sets (1: MRCP alone; 2: MRCP and DWI combined; and 3: MRCP, DWI, and contrast-enhanced T1-weighted imaging [T1WI] combined) of 60 patients with suspected distal biliary strictures and rated the probability of malignancy. Diagnostic performance and accuracy were compared using the receiver operating characteristic (ROC) curves and McNemar two-tailed test. coefficients were calculated to assess the interobserver agreement. ResultsThe Az value and accuracy improved significantly after additional review of DWI for both readers: Az=0.780 vs. 0.916 (P=0.003) for Reader 1 and 0.784 vs. 0.853 (P=0.037) for Reader 2; accuracy=69% vs. 93% for Reader 1 (P<0.001) and 57% vs. 85% for Reader 2 (P=0.002). No significant difference in the Az values and accuracy was found between MRCP and DWI combined, and MRCP, DWI, and contrast-enhanced T1WI combined (P>0.050). There was substantial interobserver agreement in all three image sets (=0.695-0.732). ConclusionThe addition of DWI to MRCP significantly improved diagnostic accuracy in the characterization of distal biliary strictures. J. Magn. Reson. Imaging 2014;39:1509-1517. (c) 2013 Wiley Periodicals, Inc.