Intravoxel incoherent motion MRI evaluation for the staging of liver fibrosis in a rat model

Purpose To explore the characteristics of intravoxel incoherent motion (IVIM) in various stages of liver fibrosis, and their relationships with fibrotic stages in rats. Materials and Methods Fifty rats were given various doses of carbon tetrachloride (CCl4) to induce various fibrotic stages in rats; 15 untreated rats served as controls. Diffusion-weighted magnetic resonance imaging (MRI) was performed and eight b-values (0–800 s/mm2) were applied to obtain IVIM parameters (D, pure molecular diffusion; f, perfusion fraction; D*, pseudodiffusion). The stages of liver fibrosis (stages F0–F4) were evaluated histologically using METAVIR scores. Fifty-seven rats (15 controls and 42 with fibrosis) were analyzed by nonparametric methods and receiver operating characteristic curves to determine diagnostic accuracy. Results Significant differences (P < 0.001) were found between stages (stages F0–F4) by D, f, D*, and apparent diffusion coefficient (ADC). There were inverse correlations between fibrosis stages and D, f, D*, ADC (r = –0.657, r = –0.631, r = –0.711 r = –0.719, respectively). Multivariate analysis showed that the combination models (D, f, D*) were better than the individual parameter (ADC) for the evaluation fibrosis stages (area under the curve [AUC]: 0.821–1.000 vs. AUC: 0.753–0.918) Conclusion IVIM-derived parameters showed significant correlations with stages of liver fibrosis in a rat model. J. Magn. Reson. Imaging 2015;42:331–339.