Noninvasive evaluation of liver fibrosis: comparison of the stretched exponential diffusion-weighted model to other diffusion-weighted MRI models and transient elastography

Objectives To compare the diagnostic performance of the stretched exponential model to those of other DWI models and transient elastography (TE) and to evaluate the influence of confounding factors on the staging of liver fibrosis. Methods This retrospective study included 78 consecutive patients who underwent both DWI and TE. The distributed diffusion coefficient (DDC) and intravoxel heterogeneity index (alpha) from the stretched exponential model, apparent diffusion coefficient (ADC), perfusion fraction (f), pseudodiffusion coefficient (D-p), true diffusion coefficient (D-t), and TE were obtained. Associations between imaging parameters and pathological fibrosis, inflammation, and steatosis were evaluated using Spearman's correlation and multiple regression analysis. Diagnostic accuracy of parameters for fibrosis staging was assessed via the Obuchowski measures. Results DDC was the only parameter to differ between F0-1 and F2-3 (p < 0.001) and between F2-3 and F4 (p = 0.013). DDC showed significant correlation with fibrosis (p < 0.001) and inflammation (p = 0.001), but not with steatosis (p = 0.619), and was independently associated with only fibrosis in multiple regression analysis (beta = - 0.114, p < 0.001). ADC, D-p, and D-t showed a significant correlation with steatosis (ps <= 0.038). DDC showed the highest diagnostic performance for liver fibrosis (0.717; 95% confidence interval, 0.653-0.765) followed by TE (0.681, 0.623-0.733) without a significant difference between DDC and TE (p > 0.999). Conclusions DDC from the stretched exponential model is the most accurate DWI parameter with no confounding effect from steatosis and with overall similar diagnostic performance to TE.

Automated summary

The distributed diffusion coefficient (DDC) from the stretched exponential model was found to be the most accurate DWI parameter for diagnosing liver fibrosis, showing significant correlation with fibrosis and inflammation but not with steatosis. DDC demonstrated similar diagnostic performance to transient elastography (TE), with no significant difference between the two methods.