Abstract: Objective The aim of this study was to analyze the diagnostic performance of liver quantitative parameters, proton density fat fraction (PDFF) obtained by magnetic resonance imaging (MRI) water-lipid separation in predicting liver steatosis in patients with non-alcoholic fatty liver disease (NAFLD). Methods A total of 106 patients with NAFLD and 30 healthy individuals were enrolled in our hospital between May 2022 and May 2025, all underwent MRI fat analysis calculation technique (FACT) to detect PDFF of the liver, and all patients with NAFLD received liver biopsy. The diagnostic efficacy of PDFF was evaluated by receiver operating characteristic (ROC) curves. Results Liver histo-pathological examination found mild liver steatosis in 56 cases, moderate in 33 cases and severe in 17 cases; PDFF in patients with NAFLD was (19.1±2.0)%, much higher than [(6.8±0.7)%, P<0.05] in healthy control; serum triglyceride, total cholesterol, low-density lipoprotein cholesterol levels and PDFF in patients with severe liver steatosis were (5.1±0.6)mmol/L, (6.6±0.8)mmol/L, (3.7±0.5)mmol/L and (24.3±2.6)%, all significantly higher than [(2.1±0.3)mmol/L, (5.5±0.6)mmol/L, (3.1±0.4)mmol/L and (17.0±1.8)%, respectively, P<0.05] in patients with mild or [(4.0±0.4)mmol/L, (6.2±0.7)mmol/L, (3.4±0.4)mmol/L and (20.1±2.1)%, respectively P<0.05] in those with moderate liver steatosis, while serum high-density lipoprotein cholesterol level was (0.8±0.1)mmol/L, significantly lower than [(1.3±0.2)mmol/L, P<0.05] in mild or [(1.0±0.1)mmol/L, P<0.05] in those with moderate liver steatosis; ROC analysis showed that the AUC was 0.865, with Youden index of 0.568, sensitivity of 80.0% and specificity of 76.8%, when PDFF, with cut-off-value of 18.8%, was applied to predict moderate/severe liver steatosis in patients with NAFLD. Conclusion PDFF arose from MRI FACT has a certain diagnostic efficacy for assessing moderate to severe liver steatosis in NAFLD patients.

Key words: Non-alcoholic fatty liver disease, Liver steatosis, Magnetic resonance imaging, Multi-echo water-lipid separation technology, Proton density fat fraction , Diagnosis