The Preliminary Study On The Quantitative Analysis Of Diffusion Kurtosis Imaging Of Liver Fibrosis In Rats

PartⅠEffect of different Regions of Interest on the consistency of Diffusion Kurtosis maging Quantitative Parameters of Rat Liver FibrosisObjective:To investigate the effect of different ROI methods on the consistency of quantitative DKI parameters in liver fibrosis of rats.Materials and Methods:Liver fibrosis in rats was induced by intraperitoneal injection of 1ml/kg 50%CCl₄ olive oil twice a week for 14 weeks,DKI was performed for all rats and 46 cases of liver fibrosis were obtained according to the analysis requirements.Two radiologists measured quantitative DKI parameters according to three ROI protocols:small solid samples、single-slice and whole-volume,the ROI of the right lobe liver fibrosis lesion was set and then quantitative DKI parameters include MD and MK were obtained.Each ROI setting method was measured three times,One radiologists repeated the method after 3 months later.The MD and MK values collected by the two physicians using each ROI setting method are the final values of MD and MK measured by the ROI setting method,The three protocols were compared for differences in MD and MK with the paired sample t test,and inter-observer variability（measured as the intra-class correlation coefficient,ICC）.Bland-Altman plot were used to measure the reproducibility of the quantitative DKI parameters too.Results:The quantitative MD parameters of small solid samples method is higher than the value of whole-volume method and the single slice method the difference is statistically significant（t=4.879、5.778,P<0.05）.the quantitative MK parameters of small solid samples method was lower than the value of whole-volume method and the single slice method the difference was statistically significant（-2.986、-3.578,P<0.05）.But the quantitative DKI parameters of whole-volume method and the single slice method showed no significant differences（t=1.888、-1.623,P value 0.061、0.107）;The intra-observer relative ICC Values of MD and MK were 0.67（0.47,0.81）and 0.53（0.28,0.72）respectively with small solid samples method;0.75（0.57,0.85）and 0.64（0.42,0.79）respectively with single slice method and 0.85（0.74,0.92）and 0.99（0.92,0.99）respectively with whole-volume method.The inter-observer relative ICC Values of MD and MK were 0.64（0.33,0.81）and 0.49（0.06,0.73）respectively with small solid samples method;0.73（0.50,0.85）and 0.65（0.35,0.81）respectively with single slice method and0.82（0.67,0.90）and 0.97（0.94,0.99）respectively with whole-volume method.Bland-Altman scattered diagram showed that the value of MD and MK measured by single slice method and whole-volume method is distribute more concentration than small solid samples means that the single slice method and whole-volume method were more consistent and reproducibility.And the DKI quantitative parameter consistency level measured by the whole-volume method was significantly higher than the single slice method.Conclusions:Different ROI methods have a certain influence on the quantitative parameters of DKI in rat liver fibrosis.In all three different ROI setting methods,the quantitative DKI parameters of whole-volume method were more consistent and reproducible.Part Ⅱ Preliminary application of MR diffusion kurtosis imaging quantitative parameters on the diagnosis of liver fibrosis in ratsObjective: To investigate the diagnostic value of the quantitative DKI parameters in the diagnosis of liver fibrosis in rats,and to evaluate the correlation between quantitative analysis of DKI and METAVIR staging.Materials and Methods: Liver fibrosis in rats was induced by intraperitoneal injection of 1ml/kg 50% CCl₄ olive oil twice a week for 14 weeks,the control group rats were intraperitoneal injected with the same dose saline and the method were the same as the experimental group.DKI was performed for all rats,and obtained 57 cases consistent with the analysis requirements of the case data,including model group（n = 46）and control group（n = 11）.The MR images were analyzed independently by one radiologists on the premise of not knowing the pathological results,and the quantitative parameters（MD and MK）and ADC value of the right hepatic lobe of the liver were measured by method in the whole volume of ROI.The MD,MK,and ADC values were compared between no fibrosis（F0）,mild fibrosis（F1-F2）and severe fibrosis（F3-F4）,and no fibrosis（F0）,non-cirrhosis（S1-3）and cirrhosis（S4）subgroups using the one way ANOVA,Additionally,receiver operating characteristic（ROC）to analyze the diagnostic efficiency of DKI and DWI.the correlation between MD,MK and ADC values of liver fibrosis and METAVIR staging was analyzed by Spearman correlation analysis.Results: The results of one way ANOVA showed that the MD,MK and ADC values of the no fibrosis（F0）,mild fibrosis（F1-F2）and severe fibrosis（F3-F4）were statistically significant（F = 103.654、6.226、41.975,P= 0.000,0.004,0.000）.Group comparison between two groups,MD: F0 and F1-F2,F0 and F3-F4,F1-F2 and F3-F4 were statistically significant（P <0.05）;MK: F0 and F3-F4,F1-F2 and F3-F4 were statistically significant（P <0.05）,F0 and F1-F2 were not statistically significant（P = 0.198）;ADC: F0 and F1-F2,F0 and F3-F4,F1-F2 and F3-F4 were statistically significant（P <0.05）.The MD,MK,ADC values of the no fibrosis（F0）,non-cirrhosis（F1-F3）and cirrhosis（F4）were statistically significant（F = 85.493、7.591、41.210,P= 0.000,0.001,0.000）.Group comparison between two groups,MD: F0 and F1-F3,F0 and F4,F1-3 and F4 were statistically significant（P <0.05）;MK: F0 and F4,F1-3 and F4 were statistically significant（P <0.05）.F0 and F1-F3 were not statistically significant（P = 0.077）;ADC: F0 and F1-F3,F0 and F4,F1-3 and F4 were statistically significant（P <0.05）.ROC curve analysis showed that MD and MK had significant difference between F0 and F1-F2,F0 and F1-F3（Z = 2.039,2.944,P <0.05）,ADC and MK were diagnosed with F0 and F1-F2 was statistically significant（Z = 2.039,P <0.05）.There was no significant difference in MD,MK and ADC between the other groups.Spearman correlation analysis showed that the MD and the staging of liver fibrosis had a strong negative correlation（r=-0.708,P < 0.05）,showed a moderate positive correlation between MK and liver fibrosis stage（r=0.420,P < 0.05）,ADC and the staging of liver fibrosis were moderate negative correlated（r=-0.624,P < 0.05）.Conclusions: The correlation between DKI parameters and METAVIR in liver fibrosis were statistically significant.The correlation between MD and liver fibrosis staging was the strongest.Therefore,DKI quantitative analysis results showed noninvasive prediction of liver Fibrosis METAVIR staging potential,were expected to become a clinical assessment of the degree of liver fibrosis potential functional imaging test indicators.