Comparison and optimization of b value combinations for diffusion-weighted imaging in discriminating hepatic fibrosis

Diffusion-weighted imaging (DWI) has shown potential in characterizing hepatic fibrosis. However, there are no widely accepted apparent diffusion coefficient (ADC) values for the b value combination. This study aims to determine the optimal high and low b values of DWI to assess hepatic fibrosis in patients with chronic liver disease.

The prospective study included 81 patients with chronic liver disease and 21 healthy volunteers who underwent DWI, Magnetic resonance elastography (MRE), and liver biopsy. The ADC was calculated by twenty combinations of nine b values (0, 50, 100, 150, 200, 800, 1000, 1200, and 1500 s/mm²).

All ADC values of the healthy volunteers were significantly higher than those of the hepatic fibrosis group (all P < 0.01). With the progression of hepatic fibrosis, ADC values significantly decreased in b value combinations (100 and 1000 s/mm², 150 and 1200 s/mm², 200 and 800 s/mm², and 200 and 1000 s/mm²). ADC values derived from b values of both 200 and 800 s/mm² and 200 and 1000 s/mm² were found to be more discriminative for differentiating the stages of hepatic fibrosis. An excellent correlation was between the ADC_200-1000 value and MRE shear stiffness (r = - 0.750, P < 0.001).

DWI offers an alternative to MRE as a useful imaging marker for detecting and staging hepatic fibrosis. Clinically, ADC values for b values ranging from 200-800 s/mm² to 200-1000 s/mm² are recommended for the assessment of hepatic fibrosis.