Experimental Study Of Contrast-enhanced Ultrasound And Shear Wave Elastography In The Assessment Of Acute Radiation-induced Liver Injury

Objective:To evaluate the microblood flow of rabbit liver after radiotherapy by quantitative analysis of contrast-enhanced ultrasound（CEUS）and to evaluate the stiffness of rabbit liver after radiotherapy by shear wave elastography（SWE）,to analysis the ability of CEUS and SWE in the estimate of radiation induced liver injury（RILI）.Methods:Twenty adult male New Zealand white rabbits were randomly divided into 3experimental groups（n=5 rabbits in each group）and 1 control group（n=5 rabbits in each group）.The liver of rabbits was given 16Gy,20Gy,24Gy doses,the field size was3.0cm×3.0cm,6MV X-ray.Mild,moderate and severe RILI models were established.What is more,the control group was given 0Gy irradiation.On the 28th day after the irradiation of rabbit livers,CEUS,SWE and liver histopathology were performed on rabbits in each group.According to the images of CEUS,the time-intensity cure（TIC）curve was depicted by the contrast-enhanced ultrasound quantitative analysis software of the machine.Time to peak（TTP）,area under the curve（AUC）,peak intensity（PI）,time from peak to one half（DT/2）of irradiated liver tissue were calculated by TIC.The maximum elastic modulus(E_max),mean elastic modulus(E_mean),and minimum elastic modulus(E_min)of liver tissue were measured in irradiated areas.The liver tissues of rabbits were taken out for pathological examination,and according to the pathological results,rabbits were re-grouped into mild RILI group,moderate RILI group and severe RILI group.To compare the degree of liver damage caused by different radiation doses and analyze the influence of different radiation doses on the degree of liver damage.To analyze the differences of CEUS and SWE parameters between the control group and different RILI groups and between different RILI groups,and to explore the application value of CEUS and SWE in different degrees of liver injury.To analyze and evaluate the correlation between CEUS and SWE parameters and the degree of liver injury and the relationship between radiation dose and the degree of liver injury.Results:1.Fisher’s exact test showed that with the increase of radiation dose,the degree of liver injury was more serious（P<0.001）.The dose was positively correlated with the degree of liver injury（r=0.920,P<0.05）.2.Compared with the parameters related to contrast-enhanced ultrasound in different injury groups,according to the time-intensity curve,TTP in different injury groups was gradually extended with the aggravation of liver injury（F=21.573,P<0.001）.Both the mild RILI group and the moderate RILI group were less than the severe RILI group.The mild RILI group was smaller than the moderate RILI group.（P<0.05）.As the degree of liver damage is aggravating,compared with control group,the PI of different RILI groups decreased（F=7.463,P<0.05）.There was no significant difference between moderate RILI group and severe RILI group,there was no significant difference among mild RILI group,moderate RILI group and severe RILI group（all P>0.05）.3.With the aggravation of liver injury,compared with the control group,the E_meanand E_max values of each RILI group increased,but E_meanand Emax gradually decreased with the increase of the degree of liver injury,and the E_mean and E_maxof the severe RILI group were still higher than the control group.（F=31.384,P<0.001,F=8.877,P<0.05）.The E_mean of mild RILI group and moderate RILI group was higher than that of severe RILI group.E_mean in mild RILI group was higher than that in moderate RILI group（all P<0.05）.The E_max value of the moderate RILI group was significantly higher than that of the severe RILI group（all P<0.05）.4.According to the Spearman correlation analysis,the conclusion can be drawn that the degree of liver injury was positively correlated with TTP（r=0.899,P<0.05）,and negatively correlated with PI,E_meanand E_max（r=-0.777,r=-0.877,r=-569,P<0.05）.Conclusion:This experiment successfully establish a rabbit radioactive liver damage model.And it found that the time to peak（TTP）of CEUS can be used to quantitatively analyze the micro-circulation changes of liver parenchyma.The mean elastic value(E_mean)of shear wave elastography can evaluate the degree of liver fibrosis by measuring liver stiffness,and then evaluate acute radiation-induced liver injury.This study preliminarily confirmed that TTP in contrast-enhanced ultrasound quantitative analysis and E_mean in shear wave elastography can both be used as indicators to evaluate the degree of acute radiation-induced liver injury,which provides a non-invasive,fast and simple examination method for the evaluation of radiation-induced liver injury.It can help clinicians detect RILI in time and carry out clinical intervention in the acute stage.Thus,it can reduce the adverse consequences caused by radioactive liver injury,which has certain significance for clinical management.