Abstract: Objective To study the best threshold value of MRI R₂^* in the staging evaluation of liver fibrosis in patients with nonalcoholic fatty liver disease (NAFLD).Methods The clinical data of 84 patients diagnosed as NAFLD in our hospital from December 2017 to December 2019 were analyzed retrospectively. According to the results of biopsy, the patients were divided into S1 group (increased fibrosis in the portal area, but only confined to the peri-sinusoid and lobule, n=23), S2 group (fibrosis around the portal area, with septal formation, but lobule structure is still intact, n=24), S3 group (lobule structure is damaged, but no cirrhosis, n=27), S4 group (early cirrhosis, n=10); R₂^* values were obtained by MRI scanning and compared among the four groups. ROC curve was used to analyze R₂^* value to predict S2, S3 and S4 stages of liver fibrosis in NAFLD patients.Results The results of R₂^* were compared between S2 group and S4 group (P<0.05). ROC analysis of R₂^* predicted that the area under the curve of S2, S3 and S4 groups were 0.748, 0.663 and 0.790 respectively.Conclusion R₂^* value has a certain predictive value to evaluate the degree of liver fibrosis in NAFLD patients, but the prediction of moderate and severe liver fibrosis needs further study.

Key words: Non-alcoholic fatty liver disease, blood oxygen level dependent MRI, Liver fibrosis stage