The Experimental Study Of Quantitative Magnetic Resonance Imaging In Evaluating Liver Fibrosis In Mice

Objective: To explore the value of MRI T1 mapping,T2 mapping,and T2* mapping in the assessment of liver fibrosis in mice.Methods: Forty-five male C57BL/6 mice were randomly divided into the normal group(N group,n = 9)and model group(M group,n = 36).Mice in the model group were intraperitoneally injected with 10% carbon tetrachloride(carbon tetrachloride,CCl4)in olive oil at a dose of 0.05ml/10 g,twice a week,to establish liver fibrosis model;mice in the normal group were injected with normal saline in the same way.At2,4 and 6 weeks after injection,twelve mice in the model group and three mice in the normal group were randomly selected for MRI examination.T1(ms),T2(ms)and T2*(ms)values of hepatic parenchyma were measured.The METAVIR system was used to classify liver fibrosis into stages F0-4.Hydroxyproline(hydroxyproline,HYP)level was detected by hydroxyproline content detection kit.The protein expression levels ofα-smooth muscle actin(α-smooth muscle actin,α-SMA),interleukin 1(interleukin 1,IL-1),interleukin 6(interleukin 6,IL-6)and tumor necrosis factor-α(tumor necrosis factor-α,TNF-α)in liver were detected by Western blot.For statistical analysis,oneway analysis of variance,Spearman rank correlation coefficient,and receiver operating characteristic(ROC)curves were performed.P < 0.05 was considered statistically significant.Results:1.With the prolongation of CCl4 administration,liver fibrosis development showed an upward trend,and the levels of liver fibrosis markers increased simultaneously.2.After comparing parameter values at different time points,T1 values of the mice in the model group were significantly higher than those of the normal group at different time points,and T2 values were significantly higher at week 2 and week 6(P < 0.05).However,there was no significant difference in liver T2* values among the two groups at different time points(P > 0.05).3.The histopathological results of all mice were as follows: F0 = 9(all in the normal group),F1 = 8,F2 = 6,F3 = 10,and F4 = 12.4.T1 values showed a significant positive correlation with the stages of liver fibrosis,HYP,IL-1,IL-6,and TNF-α(ρ = 0.854,0.883,0.804,0.751,0.940,all P < 0.001);T2 values showed a moderate positive correlation(ρ = 0.697,0.595,0.610,0.550,0.763,all P < 0.05),while T2* values showed poor correlations and had no statistical significance.5.The AUC ranges of T1,T2,and T2* for diagnosing ≥ F1,≥ F2,≥ F3,and F4 were successively as follows: T1 values(0.842-0.994)> T2 values(0.808-0.883)> T2*values(0.522-0.692),where T1 and T2 values showed similar high diagnostic efficacy in differentiating stages(all P > 0.05).Conclusions: T1 mapping and T2 mapping expected to be a valuable diagnostic tools for the detection and quantification of liver fibrosis in the CCl4-induced model.T1 correlated better with collagen deposition and inflammation of liver fibrosis than T2.T2* mapping was of limited value in the staging assessment of liver fibrosis.