MRI-based Staging of Hepatic Fibrosis: Comparison of Intravoxel Incoherent Motion Diffusion-weighted Imaging with Magnetic Resonance Elastography

Purpose: To evaluate the use of intravoxel incoherent motion (IVIM) imaging for staging hepatic fibrosis, and compare its staging ability with that of magnetic resonance elastography (MRE).

Materials And Methods: This study included 129 patients with pathologically staged liver fibrosis, and 53 patients with healthy livers. All patients underwent both MRE and IVIM imaging. Four diffusivity indices were calculated with 11 b-values; slow diffusion coefficient related to molecular diffusion (D), fast diffusion coefficient related to perfusion in micro-vessels (D*), perfusion-related diffusion fraction (f), and apparent diffusion coefficient (ADC). Receiver operating characteristic curve analysis was performed to determine the accuracy of IVIM imaging and MRE for staging hepatic fibrosis.

Results: D*, f, and ADC values decreased significantly with fibrosis stage (P < 0.0124), and liver stiffness increased (P < 0.0001). The Az value of MRE was significantly higher than that of D* for all fibrosis stages (D* vs. MRE for ≥ F1, 0.851 vs. 0.992 [P < 0.0001]; ≥ F2, 0.898 vs. 0.998 [P = 0.0003]; ≥ F3, 0.904 vs. 0.995 [P = 0.0004]; F4, 0.885 vs. 0.996 [P < 0.0001]).

Conclusion: IVIM imaging is a useful technique for evaluating hepatic fibrosis, but MRE is better able to discriminate fibrosis stages than IVIM imaging.