Assessment of Liver Fibrosis with Diffusion-Weighted Magnetic Resonance Imaging Using Different b-values in Chronic Viral Hepatitis
Objective: To examine the effectiveness of apparent diffusion coefficient (ADC) values and to compare the reliability of different b-values in detecting and identifying significant liver fibrosis. Subjects and Methods: There were 44 patients with chronic viral hepatitis (CVH) in the study group and 30 healthy participants in the control group. Diffusion-weighted magnetic resonance imaging (DWI) was performed before the liver biopsy in patients with CVH. The values of ADC were measured with 3 different b-values (100, 600, 1,000 s/mm<sup>2</sup>). In addition, liver fibrosis was classified using the modified Ishak scoring system. Liver fibrosis stages and ADC values were compared using areas under the receiver-operating characteristic (ROC) curve. Results: The study group's mean ADC value was not statistically significantly different from the control group's mean ADC value at b = 100 s/mm<sup>2</sup> (3.69 ± 0.5 × 10<sup>-3</sup> vs. 3.7 ± 0.3 × 10<sup>-3</sup> mm<sup>2</sup>/s) and b = 600 s/mm<sup>2</sup> (2.40 ± 0.3 × 10<sup>-3</sup> vs. 2.5 ± 0.5 × 10<sup>-3</sup> mm<sup>2</sup>/s). However, the study group's mean ADC value (0.99 ± 0.3 × 10<sup>-3</sup> mm<sup>2</sup>/s) was significantly lower than that of the control group (1.2 ± 0.1 × 10<sup>-3</sup> mm<sup>2</sup>/s) at b = 1,000 s/mm<sup>2</sup>. With b = 1,000 s/mm<sup>2</sup> and the cutoff ADC value of 0.0011 mm<sup>2</sup>/s for the diagnosis of liver fibrosis, the mean area under the ROC curve was 0.702 ± 0.07 (p = 0.0015). For b = 1,000 s/mm<sup>2</sup> and the cutoff ADC value of 0.0011 mm<sup>2</sup>/s to diagnose significant liver fibrosis (Ishak score = 3), the mean area under the ROC curve was 0.759 ± 0.07 (p = 0.0001). Conclusion: Measurement of ADC values by DWI was effective in detecting liver fibrosis and accurately identifying significant liver fibrosis when a b-value of 1,000 s/mm<sup>2</sup> was used.