Abstract: Objective This study was conducted to explore the qualitative diagnostic efficacy of focal nodular lesions of liver (FNLL) by magnetic resonance imaging (MRI) in patients with nonalcoholic fatty liver diseases(NAFLD). Methods A total of 113 patients with FNLL under the background of NAFLD were enrolled in our hospital between December 2019 and December 2022, and all patients were examined by diffusion-weighted magnetic resonance imaging (MRI-DWI) and dynamic enhanced magnetic resonance imaging (DCE-MRI), with the time-signal curve types recorded. The fine needle aspiration biopsy was performed for pathological diagnosis as the gold standard. The consistency of diagnoses by MRI-DWI and DCE-MRI with the gold standard was compared by Kappa test. Results Out the 113 patients with FNLL and NAFLD, the pathological examination showed focal nodular hyperplasia (FNH) in 69 cases and hepatocellular carcinoma (HCC) in 44 cases; the percentages of typeⅠ, type Ⅱ and type Ⅲ of time-signal curve in malignant lesions were 38.6%, 52.3% and 9.1%, significantly different compared to 2.9%, 20.3% and 76.8% in benign lesions (P＜0.05); the sensitivity, specificity and accuracy were 93.2%,100.0% and 97.3% when the qualitative diagnosis was made by the combination of MRI-DWI and DCE-MRI, much superior to 90.9%, 88.4% and 89.4% by DCE-MRI alone or 90.9%,91.3% and 91.2% by MRI-DWI alone (P＜0.05). Conclusion Theapplication of MRI, especially with DCE-MRI and MRI-DWI models, in the qualitative diagnosis of FNLL under the background of NAFLD is efficacious, which might help the clinicians make a correct diagnosis and deal with appropriately.

Key words: Hepatoma, Focal nodular lesion of liver, Nonalcoholic fatty liver diseases, Dynamic enhanced magnetic resonance imaging, Diffusion-weighted imaging, diagnosis