Evaluation Of Left Ventricular Myocardial Injury After Intensity Modulated Radiation Therapy For Thoracic Tumor By Speck-tracking Layer-special Strain

Objective:A new technique of speck tracking layer-special strain was used to assess the myocardial function impairment of left ventricle in early subclinical stage after intensity modulated radiation therapy in patients with thoracic malignancy Materials and methods:A total of 35 patients with malignant tumor who received thoracic radiotherapy for the first time were selected as the radiotherapy group.Echocardiography was performed before radiotherapy（T0）,at the end of radiotherapy（T1）,and 3 months after radiotherapy（T2）.Twenty-five patients who underwent physical examination in our hospital during the same period were selected as the control group（T）.Echocardiography was performed on the out-patient（T）.In this study,stratified strain technique was used to analyze the peak longitudinal strain（PLS-endo,PLS-mid,PLS-epi,PLS）of the myocardium in the basal,middle and apical segments of the left ventricle.At the same time,the longitudinal strain of global peak value in systolic period of the left ventricle（GLS-endo GLS-mid GLS-epi GLS）was analyzed.The longitudinal strain rates（GLS-endo% GLS-mid% GLS-epi %）of each myocardium at the end of radiotherapy（T1）and 3 months（T2）were calculated compared with those before radiotherapy（T0）.Pearson correlation analysis was used to analyze the relationship between △ GLS-endo % and MHD,V5,V30.Result 1.There were no significant differences in gender,age,height,weight,BMI,heart rate,systolic blood pressure,diastolic blood pressure,smoking history,diabetes and hypertension between radiotherapy group and control group（P > 0.05）.2.Compared with the control group（T）,there were no significant differences in conventional cardiogram indexes and strain parameters indexes before radiotherapy（T0）in radiotherapy group（P > 0.05）.3.Conventional ultrasound parameters of the radiotherapy group:Compared with before radiotherapy（T0）,conventional parameters such as AO,LA,IVSd,LVIDd,LVPWd,E,A,E/A,E ’（m）,E’（L）,E/ E ’,AND LVEF at the end of radiotherapy（T1）and 3 months after radiotherapy（T2）showed no statistical difference（P>0.05）.However,with the progress of radiotherapy,LVEF has declined.4.Intrasegmental,middle,external and full-layer strains of radiotherapy group:（1）Compared with before radiotherapy（T0）,the peak longitudinal strain of systolic period（PLS-endo,PLS-mid and PLS-epi）in the myocardium of basal segment,middle segment and apical segment at the end of radiotherapy（T1）and 3 months after radiotherapy（T2）were decreased;Pls-endo,PLS-mid and PLS-epi were further decreased at 3months after radiotherapy（T2）compared with that at the end of radiotherapy（T1）,and the differences were statistically significant（P <0.05）.The absolute values of PLS-endo,PLS-mid and PLS-epi in basal segment,middle segment and apex segment decreased layer by layer,and the differences were statistically significant（P < 0.05）.（2）Compared with before radiotherapy（T0）,full-layer peak longitudinal strain（b PLS,m PLS,a PLS）in basal segment,intermediate segment and apical segment decreased at the end of radiotherapy（T1）and3 months after radiotherapy（T2）;At 3 months after radiotherapy（T2）,compared with the end of radiotherapy（T1）,b PLS,m PLS and a PLS were further reduced,and the differences were statistically significant（P <0.05）.The absolute value of full-layer longitudinal peak systolic strain（b PLS,m PLS,a PLS）increased from basal segment to apex segment,and the difference was statistically significant（P < 0.05）.5.Overall internal,middle,external and full-layer strain in radiotherapy group:Compared with before radiotherapy（T0）,the overall systole peak longitudinal strain（GLS-endo、GLS-mid、GLS-epi、GLS）of endocardial layer,middle layer and epicardium layer and whole layer at the end of radiotherapy（T1）and 3 months after radiotherapy（T2）decreased;Compared with the end of radiotherapy（T1）,Gls-endo,GLS-mid,GLS-epi and GLS were further decreased at 3 months after radiotherapy（T2）and the difference was statistically significant（P < 0.05）.The absolute values of GLS-endo,GLS-mid and GLS-epi decreased layer by layer,and the difference was statistically significant（P < 0.05）.6.The percentage of GLS-endo% GLS-mid % GLS-epi % decreased successively at the end of radiotherapy（T1）and 3 months after radiotherapy（T2）,and the differences were statistically significant（P<0.05）.7.At 3 months after radiotherapy（T2）,△ GLS-endo % was positively correlated with MHD,V5,V30 in patients with chest tumor after intensity modulated radiotherapy（r = 0.58,0.65,0.68,P < 0.05）.Conclusion:1.Two-dimensional layered strain technique can sensitively reflect the local and overall changes of left ventricular myocardium in the early stage after radiotherapy in patients with thoracic malignant tumor.2.Subclinical dysfunction may occur in all three layers of myocardium after radiotherapy,especially in the endocardium.3.△GLS-endo% and GLS-endo can be used to assess the myocardial systolic function of left ventricle sensitively at an early stage.4.The degree of myocardial injury was positively correlated with the cumulative radiation dose of left ventricle...