The Value Of Two-dimensional Shear Wave Elastography In Monitoring Brachial Plexus Elasticity After Radiotherapy For Breast Cancer

Objective: Two-dimensional shear wave elastography(2D-SWE)was used to analyze the elastic characteristics of brachial plexus in patients with breast cancer after radiotherapy,and compared with healthy volunteers,in order to evaluate whether the elastic characteristics can be used as a basis for early diagnosis of brachial plexus involvement in patients with radiotherapy.The correlations between follow-up time after radiotherapy,brachial plexus radiation volume,radiation dose and brachial plexus elastic modulus,shear wave velocity(SWV)in patients with breast cancer were analyzed.Methods: This study included 84 patients with breast cancer after postoperative radiotherapy and 40 healthy female volunteers.The thickness,perimeter and cross-sectional area of brachial plexus were measured by high frequency ultrasound,and the elastic modulus and SWV of brachial plexus were measured by 2D-SWE technique.According to the severity of clinical symptoms,all patients with breast cancer were divided into three groups: group A was mild sensory disturbance,pain-free and did not need treatment,group B was moderate sensory disturbance,pain tolerance and mild arm weakness,and group C was persistent anaesthesia with incomplete paralysis and painkillers.The thickness,perimeter,cross-sectional area,elastic modulus and SWV of brachial plexus among the four groups were compared by one-way analysis of variance;draw the receiver operating characteristic curve(ROC)of elastic modulus and SWV;the follow-up time after radiotherapy,brachial plexus radiation volume and dose of breast cancer patients were recorded,and the correlation between brachial plexus elastic modulus and SWV and the above factors were discussed.Statistically significant difference of P<0.05.Results:1.There was no significant difference in the thickness of brachial plexus among all groups(P > 0.05).There was no significant difference in the perimeter and cross-sectional area of brachial plexus between group A and control group,group B and group C(P>0.05),but the perimeter and cross-sectional area of brachial plexus in group B and C were significantly higher than those in group A and control group(P<0.05),the difference was statistically significant(P<0.05).The values of elastic modulus and SWV of brachial plexus in group A,B and C were higher than those in control group,the values of elastic modulus and SWV in group B and C were higher than those in group A,and the values of elastic modulus and SWV in group C were higher than those in group B,the differences were statistically significant(P<0 05).2.The two elastic parameters of the brachial plexus,namely the elastic modulus and SWV,the area under the curve were 0.824 and 0.829,respectively.The best cut-off value of elastic modulus for the diagnosis of brachial plexus involvement is28.65 k Pa,the sensitivity and specificity are 80.0% and 70.6%,respectively,and the best cut-off value of SWV for brachial plexus involvement diagnosis is 3.1m/s,and the sensitivity and specificity are 74.0% and 76.5%,respectively.3.The results of Spearman correlation analysis showed that the follow-up time after radiotherapy,brachial plexus radiation volume and dose of breast cancer patients were correlated with brachial plexus elastic modulus(r=0.333,0.414,0.465,P<0.05)and SWV(r=0.345,0.421,0.482,P<0.05).Conclusion: Postoperative radiotherapy of breast cancer can increase the hardness of brachial plexus,and the course of disease,brachial plexus radiation volume and dose can affect brachial plexus elasticity.2D-SWE technique can noninvasively and quantitatively evaluate the elastic changes of brachial plexus and provide supplementary information for clinical diagnosis of brachial plexus involvement.