Role of diffusion-weighted magnetic resonance imaging in the diagnosis of gallbladder cancer

Purpose: To determine the additional diagnostic value of high b-value diffusion-weighted imaging (DWI) compared to conventional biliary magnetic resonance imaging (MRI) for differentiating gallbladder (GB) cancer from benign GB diseases with wall thickening. Materials and Methods: Thirty-nine patients with GB cancers and 36 patients with cholecystitis having preoperative biliary MRIs were included. All patients underwent unenhanced T1-and T2-weighted imaging (T2WI), Gdenhanced dynamic MRI, and DWI (b values 0, 100, 500, 1000 s/mm 2). Two radiologists independently analyzed two sets of MRI for characterization of GB lesions: a conventional biliary image (CBI) set with T1-and T2WI and a dynamic image; and a DWI set composed of DWI and a CBI set. Diagnostic accuracy and sensitivity were evaluated using the receiver operator characteristic method. The mean apparent diffusion coefficient (ADC) values of the lesions were also calculated. Results: The Az values were 0.856 and 0.960 for reviewers 1 and 2, respectively, with the CBI set and increased to 0.952 and 0.983 with the DWI set. The mean ADC value of GB carcinoma was 1.46 +/- 0.45 x 10(-3) mm(2) /s and that of cholecysititis was 2.16 +/- 0.56 x 10(-3) mm(2) /s (P < 0.0001). Conclusion: Adding DWI to the standard biliary MRI protocol may improve sensitivity for distinguishing GB cancers from benign GB diseases with wall thickening.