Experimental Study Of 3.0T Dynamic Contrast-enhanced Magnetic Resonance Imaging In Evaluating Liver Fibrosis Staging

ObjectiveTo explore the feasibility of dynamic contrast-enhanced magnetic resonance imaging（DCE-MRI）quantitative parameters to evaluate the staging of liver fibrosis,to find the optimal magnetic resonance index to reflect the stage of liver fibrosis.Materials and MethodsA total of 65 New Zealand rabbits were selected in this study.The experimental group（n=55）and the control group（n=10）were used to establish the model of hepatic fibrosis by injecting 40%CCl4 mix with olive oil by intraperitoneal injection.the rabbits underwent dynamic contrast-enhanced magnetic resonance imaging（DCE-MRI）In the 6,8,10,12,and 16 weekend by batch,and the contrast agent was Gadolinium-diethylene-triamine penta-acetic acid（Gd-DTPA）.Then through post-processing,theliver DCE-MRIquantitative parameter:K^trans（forward volume transfer constant）,K_ep（rate constant）and V_e（extravascular extracellular space leakage space）were got.The animals were killed immediately after scan,And their livers were kept for HE and MASSON staining,and rabbit livers fibrosis evaluation were performed based on the METAVIR staging systemfibrosis stages.TheDCE-MRI data were analyzed by SPSS17.0 statistical software package.DCE-MRI quantitative parameters K^trans,V_e,K_epp results expressed as mean±standard deviation,The parameters in each groups was compared with（One-way ANOVA）analysis of variance.The Spearman correlation analysis was used to evaluate the relationship between the above parameters and liver fibrosis staging.Result1、The animals of experimental group begin death after giving the drug,,the 5 to 7 weeks of death peak.Final pathologic stage:F0:9,F1:8,F2:7,F3:9,F4:8,the Experimental group mortality rate 34.5%,the control group all survived.2、With the progress of the liver fibrosis（F0-F4）,K^trans、and K_epp gradually reduce,K^transrans is（0.557±0.080、0.503±0.076、0.468±0.046、0.411±0.058、0.367±0.075）min-1,K_epis（2.028±0.360、1.943±0.227、1.908±0.234、1.717±0.151、1.546±0.261）min-1.V_e gradually increased,which is（0.217±0.076、0.250±0.077、0.270±0.079、0.275±0.069、0.284±0.087）.（One-way ANOVA）analysis of variance,the stages of liver fibrosis:compared with control group the results of DCE-MRI quantitative parameters show that the K^trans、K_epp compared statistically significant between groups,and V_e is not statistically significant between groups.The difference of K^transrans in F0 vs F1-2、F0 vs F3-4、F1-2 vs F3-4、F0 vsF1-4、F0-2 vs F3-4 were statistically significant（P<0.05）,The difference of K_epp in F0 vsF3-4、F1-2 vs F3-4、F0 vsF1-4、F0-2 vs F3-4 were statistically significant（P<0.05）,The difference of K_epp in F0 vs F1-2 was not statistically significant（P>0.05）3、K^trans、K_epp were negativecorrelation with liver fibrosis staging（r=-0.739,r=-0.530,P<0.005）,V_e showed positive correlation with liver fibrosis staging（r=0.306,p<0.05）.4、Using ROC analysis,the area under curve（AUC）for identifying F0 vs F1-4、F0 vs F1-2、F0 vs F3-4、F0-2 vs F3-4were 0.878、0.770、0.967 and 0.898respectively by K^trans,the AUC for identifying F0 vs F1-4、F0 vs F1-2、F0 vs F3-4、F0-2 vs F3-4 were 0.699、0.563、0.810 and 0.820 respectively by K_ep.Conclusion1.The K^transrans and K_epp values of DCE-MRI were negatively correlated with the stage of liver fibrosis,and the value of V_e was positively correlated with the stage of liver fibrosis.2.K^transrans can be used for the identification of normal liver and liver fibrosis,K^trans,K_epp can be used for the identification of non advanced hepatic fibrosis（F0-2）and advanced liver fibrosis（F3-4）,K^transrans is better than K_epp to diagnose liver fibrosis,V_e cannot be used to diagnose of liver fibrosis.