Comparison of the Effects of Hepatic Steatosis on Monoexponential DWI, Intravoxel Incoherent Motion Diffusion-weighted Imaging and Diffusion Kurtosis Imaging

Rationale and objectives: Diffusion-weighted imaging (DWI) techniques have drawn attention for their capability of staging hepatic fibrosis. However, the diagnostic performance of DWI for hepatic fibrosis might be affected by hepatic steatosis because hepatic steatosis and fibrosis may have a similar effect on diffusion/perfusion parameters. Therefore, the purpose of our study is to investigate the effect of hepatic steatosis on DWI parameters.

Materials and methods: 51 patients with MR elastography liver stiffness values below 3.45kPa underwent DWI with multiple b-values and a multi-echo Dixon sequence for fat quantification. Correlation analysis was conducted between fat fraction and DWI parameters, and DWI parameters were compared between steatosis and non-steatosis groups.

Results: Significant negative correlation was observed between fat fraction and apparent diffusion coefficient (ADC) (r = -0.62, p <0.001), pure molecular diffusion (D) (r = -0.62, p <0.001), corrected ADC (D_app) (r = -0.36, p = 0.01) and a positive correlation with mean kurtosis (K_app) (r = 0.53, p <0.001). The results of the comparison of DWI parameters were that ADC, D and D_app were statistically lower in the steatosis group (p < 0.001, p < 0.001 and p = 0.026, respectively) and K_app was significantly higher in the steatosis group (p <0.001) compared to the non-steatosis group. However, perfusion-related parameters (D* and f) did not show any statistical significance.

Conclusion: DWI parameters except for perfusion-related parameters (D* and f) are affected by changes in hepatic steatosis. Thus, hepatic steatosis may be considered as a possible confounding factor in DWI-based assessment of liver fibrosis.