Study On The Correlation Between Magnetic Resonance DWI,IVIM And Pathological Stages Of Hepatic Fibrosis In Rats

Objective To evaluate the correlation between the parameter ADC of Diffusion Weighted Imaging?DWI?,the parameters D,f,D * of Intravoxel Incoherent Motion?IVIM?and thepathological stage of hepatic fibrosis in rats and the best indicator in diagnosis and staging liver fibrosis.Methods 65 healthy and clean SD rats were obtained from the experimental animal center of Lanzhou University,Fifty rats were randomly selected as experimental groups,the remaining 10 rats were used as healthy controls.Using Classical culture method,,Rats in the experimental group were induced to different levels of hepatic fibrosis by intraperitoneal injection of carbon tetrachloride.Another ten healthy rats were fed normally.3.0T MRI were performed in two groups rats successively.The sequences included conventional Axial T1 weighted imaging?TIWI?,Axial T2-weighted imaging?T2WI?,Axial DWI?b=0s/mm²,800s/mm²?and Axial IVIM?b=0s/mm²,50s/mm²,100s/mm²,150s/mm²,200s/mm²,400s/mm²,600s/mm²,800s/mm²?.DWI parameter?ADC,apparent diffusion coefficient?and IVIM parameters?D,pure molecular diffusion;f,perfusion fraction;D*,pseudo diffusion?were obtained.All rats were executed after MR scan to performe the liver histopathological examination.The pathologic grading of hepatic fibrosis was divided into F0-F4 stage according to the Metavir score system.Fifty-five rats?4 rats died and 6 were excluded with poor image quality in the experimental group?were divided into five groups according to the pathological stage.Measured the parameters of each group of DWI,IVIM imaging,use SPSS 22.0 for data analysis,Evaluate the diagnostic accuracy of ADC,D,f and D* using the receiver operating characteristic curve?ROC?.Result:1.Pathological staging resultsIn 45 liver fibrosis rats,Pathological results is F1 stage 8,F2 stage 13,F3 stage 14,F4 stage 10;10 healthy rats of control group were classified into F0.2.Comparison of DWI and IVIM parameters between normal rats and liver fibrosis ratsResults showed the ADC values of the normal and hepatic fibrosis rats were significantly higher than D values(ADC and D values in the normal rats were?1.35±0.08?x10^-3mm²/s and?0.99±0.08?x10^-3mm²/s,respectively,P<0.05)(ADC and D values in the hepatic fibrosis rats were?1.25±0.10?x10^-3mm²/s and?0.88±0.69?x10^-3mm²/s,re-spectively,P<0.05).The ADC value and D value of fibrosis group were?1.25 ± 0.10?.The ADC,D,f and D * values of fibrosis rats were significantly lower than those of normal rats?P<0.01?.Spearman correlation analysis showed that ADC,D,f and D* values were negatively correlated with liver fibrosis?r =-0.657,r =-0.668,r =-0.711,r =-0.851,P < 0.05?,D* values have the highest correlation with the degree of liver fibrosis.3.The identification ability of DWI and IVIM parameters between the fibrosis stagesIn the DWI single-index model,with the development of liver fibrosis,ADC value showed a decreasing trend,among which F3 and F4 ADC values were significantly different(?1.23±0.11?x10^-3mm²/s and?1.16±0.05?x10^-3mm²/s,P<0.05),There was no significant differ ence in ADC values between F0 and F1,F1 and F2,F2 and F3.In the IVIM double exponential model,D,f,D* values decreased gradually with the liver fibrosis stage increased,the D* of F0 and F1 stage were significantly differences(D*values are respectively?59.88±6.93?x10^-3mm²/s and?49.37±5.19?x10^-3mm²/s,P<0.01);the D* and f of F1 and F2 stage were significantly differences(D* values are respectively?49.37±5.19?x10^-3mm²/s and?42.69±2.75?x10^-3mm²/s,P<0.01),f values are respectively?0.24±0.03?and?0.21±0.02?,P<0.01).the D of F3 and F4 stage were significantly differences(respecti vely?0.88±0.05?x10^-3mm²/s and?0.90±0.06?x10^-3mm²/s,P<0.05).4.The diagnosis accuracy of DWI and IVIM parameters for different stages of liver fibrosisStatistical analysis,D*value in the liver fibrosis F0 and F1-4,F0-1 and F2-4,F0-2 an d F3-4 phase of the differential diagnosis were better than the ADC value and D,f value,the area under the ROC curve was 0.982,0.980 and 0.930,respectively.The thresholdsof each group were 49.82x10^-3mm²/s,44.70x10^-3mm²/s and 42.15x10^-3mm²/s respectively,thesensitivity was 93%,95% 92%,specificity were 100%,94% and 83% respectively,and t he Youden index were 0.930,0.892 and 0.755 respectively.In the F0-3 and F4 liver fibrosis differential diagnosis,ADC value has a high diagnostic efficiency,ROC curve area of 0.911,ADC threshold of 1.17x10^-3mm²/s,the sensitivity of 80%,specific The degree is 93% and the Jordanian index is 0.730.Conclusion:1.Both ADC and D* can diagnose and staging liver fibrosis,but D* is better than ADC2.Parameters of DWI and IVIM were negatively correlated with the level of liver fibrosis;D* values have the highest correlation with the degree of liver fibrosis.3.D* can identify liver fibrosis F0 and F1,D * and f can identify liver fibrosis F1 and F2,ADC and D can identify F3 and F4 stage of liver fibrosis.ADC,D,f and D* are valuable for the diagnosis and staging of hepatic fibrosis,With D* has the best performance.