Objective To explore the values of metrics on intravoxel incoherent motion (IVIM) and gadoxetic acid enhanced T1ρ imaging for staging of non-alcoholic fatty liver disease activity scores (NAS) and inflammation in nonalcoholic steatohepatitis (NASH) rabbits model. Methods NASH rabbits model was established by feeding with a varied duration (4, 8, 12 weeks) of high-fat, high-cholesterol diet. IVIM and gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) enhanced T1ρ images were performed by a 3.0 T MR scanner. The inter-class correlation coefficients (ICC) and Bland-Altman analysis were applied to evaluate the reproducibility of the IVIM and Gd-EOB-DTPA enhanced T1ρ mapping measurers. Spearman correlation analysis were used to assess the correlation between MR metrics, including ADC, D, D*, f, T1ρ, T1ρ (hepatobiliary phase, HBP), and NAS score and inflammation grades respectively with reference to histopathology. ROC curve analysis was used to evaluate the diagnostic performance of T1ρ and IVIM parameters for NASH, inflammation grade, and hepatic fibrosis. Multiple linear regression equations were used to analyze the independent influence factors of T1ρ (HBP). Results The f value was negatively correlated with the NAS score (r=-0.530, P<0.01). The f value of the fibrosis S1-2 was significantly lower than that of the S0 (P<0.01). There was no statistical difference in D, D*, ADC among NASH score, inflammation, and fibrosis stage. T1ρ and T1ρ (HBP) values were positively correlated with NAS scores and inflammation grades. The area under curve (AUC) for the diagnosis of NASH for T1ρ, T1ρ(HBP), ADC, D, D*, and f values were 0.849, 0.949, 0.728, 0.596, 0.522, and 0.871, respectively. The AUCs of T1ρ (HBP)+f in the diagnosis of NASH, G2-3 inflammation, and F1-2 fibrosis were 0.971, 0.935, and 0.903, respectively. Fibrosis (R2=0.624, P=0.002) and inflammation (R2=0.746, P=0.002) were major independent factors of T1ρ (HBP). Conclusion Gd-EOB-DTPA enhanced T1ρ imaging can reflect the severity of NASH and degree of inflammation. IVIM measurements are not accurate enough to stage liver inflammatory activity of NASH. T1ρ (HBP)+f might be a superior noninvasive imaging biomarker than either non-enhanced T1ρ or IVIM for NASH activity and inflammation assessments. Key words: Magnetic resonance imaging; Nonalcoholic steatohepatitis; Intravoxel incoherent motion; Gadoxetate acid disodium
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