Added value of diffusion-weighted imaging to MR cholangiopancreatography for the diagnosis of bile duct dilatations.

Abstract

To investigate the added value of diffusion-weighted imaging (DWI) when used with conventional T2-weighted magnetic resonance (MR) imaging (T2WI) and MR cholangiopancreatography (MRCP) for diagnosing bile duct dilatations. Our institutional review board approved this retrospective study protocol and waived the informed consent requirement. The study included 151 consecutive patients (70 men, 81 women) with intra- and/or extra-hepatic bile duct dilatation examined using MR imaging. Two radiologists independently and randomly reviewed 3 image sets (A: MRCP and T2WI; B: DWI; and C: combined T2WI, MRCP, and DWI) at different occasions to differentiate between malignancy, biliary lithiasis, and benign dilatation. The sensitivity, specificity, and diagnostic accuracy of these imaging sets were calculated and compared. For both readers, combined T2WI, MRCP, and DWI exhibited significantly higher sensitivity and diagnostic accuracy for malignant dilatation, compared with conventional T2WI and MRCP (P<0.01 for both readers). However, DWI did not significantly affect the sensitivity and diagnostic accuracy for biliary lithiasis or benign dilatation. The addition of DWI to T2WI and MRCP sequences yields significantly higher sensitivity and diagnostic accuracy when examining bile duct dilatations, particularly malignant dilatations.