Diffusion-Weighted Magnetic Resonance Imaging for Diagnosis of Liver Fibrosis and Inflammation in Chronic Viral Hepatitis: The Performance of Low or High b Values and Small or Large Regions of Interest

Abstract Objective To investigate the performance of different b values and regions of interest (ROI) for diagnosing liver fibrosis in patients with chronic viral hepatitis by using diffusion-weighted (DW) magnetic resonance imaging (MRI). Methods Eleven healthy participants and 33 patients with viral hepatitis B or C were enrolled. The stage of liver fibrosis and the grade of necroinflammation were determined by using a histologic activity index. Single-shot spin-echo echo-planar DW-MRI was performed in all participants at b values of 0-500, 0-700, and 0-1000 s/mm2 by using 2 circular small and large ROIs of 100 and 200 mm2 . To evaluate the performance of different b values for determining cirrhosis, the receiver-operating characteristic curves were depicted, and the areas under the curves were compared. Results The average values of apparent diffusion coefficients significantly decreased with increasing stage or grade categories at all the 3 b values and for both small and large ROIs. The performance at b = 500 s/mm2 was significantly better than b = 1000 s/mm2 for determining cirrhosis or bridging fibrosis. The cut point of 153.4 for apparent diffusion coefficient (×10−5 mm2 /s) at b = 500 s/mm2 could determine cirrhosis or bridging fibrosis with a sensitivity of 96% and specificity of 82%. No difference was found between the average apparent diffusion coefficient values of large or small ROIs. Also, there was no difference in performance of large or small ROIs in the diagnosis of liver fibrosis. Conclusions This study provided beneficial data for clinical utilisation of DW-MRI in diagnosing liver fibrosis: b = 500 s/mm2 is better in performance than b = 1000 s/mm2 , and a small ROI of 100 mm2 is sufficient for determining cirrhosis or bridging fibrosis.