Quantitative Evaluation Of Pectoralis Major Stiffness Changes In Breast Cancer Patients Undergoing Postoperative Radiotherapy By Shear Wave Elastography

Objective:Shear Wave Elastography(SWE)was used to dynamically monitor the effect of postoperative radiotherapy on pectoralis major muscle stiffness in breast cancer patients,and observe the changes of pectoralis major muscle stiffness at different times before and after treatment,so as to provide imaging basis for clinical evaluation of pectoralis major muscle injury.Methods:A total of 76 female breast cancer patients(case group)who underwent surgery and radiotherapy in our hospital were selected,and 38 cases were divided into breast-conserving group and 38 cases in radical mastectomy group according to different surgical methods,and 40 healthy female volunteers were selected as the control group during the same period.SWE was used to measure the shear wave velocity(SWV)of the pectoralis major muscle clavicular and sternocostal region at 1 week,3months,and 6 months before treatment(preoperatively)and after treatment(after surgery plus radiotherapy)in the control group and the case group,respectively.At the same time,SWE technology was used to randomly select 10 subjects from the control group,breast-conserving group and radical resection group to study the reliability of pectoralis major muscle remeasurement,and the SWV of the above three groups of pectoralis major muscle clavicle and chest rib was measured twice by the same physician within 24 hours,and the reliability of SWV retest in the two examinations before and after was evaluated by Intra-class Correlation Coefficient(ICC).Then,the changes of pectoralis major muscle SWV values in different parts before and after treatment were compared and analyzed in each group,and the differences in the SWV of the clavicular and sternocostal region of the affected side after treatment were analyzed in different surgical groups.Statistical methods corresponding to data types were used for statistical analysis,and the difference was statistically significant with P<0.05.Results:1.Use SWE to quantify the reliability of retest SWV of the pectoralis major muscle at different sites: the reliability of repeatability measurements in the control group,breast-conserving group and radical resection group was excellent in the testers at the clavicular and sternocostal region of the pectoralis major muscle(ICC> 0.90,95% CI).2.Comparison of preoperative pectoralis major SWV between control groups,breast-conserving group and radical resection group: there was no significant difference in SWV between and within the group(all P>0.05),there was no significant difference in SWV between and within the group(all P>0.05),and the SWV of the pectoralis major muscle clavicular region was higher than that in the pectoralis major muscle sternocostal region(all P<0.05).3.Comparison before and after treatment of pectoralis major muscle SWV in different parts of breast-conserving group and radical resection group: SWV of pectoralis major muscle clavicular and sternocostal region on the affected side was higher than that of the healthy side at 1 week,3months and 6 months after breast-conserving group and radical resection radiotherapy,and the differences were statistically significant(all P<0.05).The SWV of the clavicular and sternocostal region of the affected pectoralis major muscle in the breast-conserving group and radical resection group gradually increased with the extension of the time after radiotherapy,among which the SWV of the clavicular region of the affected pectoralis major muscle was higher than that of 1 week,3 months and 6 months after radiation therapy of the pectoralis major muscle of the affected side than before treatment,and the SWV of 1 week,3 months and6 months after radiation therapy of the pectoralis major muscle on the affected side was higher than that before treatment,and the difference was statistically significant(all P<0.05).4.Comparison of SWV of pectoralis major muscle in different parts of the affected side after radiotherapy in breast-conserving group and radical resection group: Compared with the SWV of the clavicular region of the affected side at 1 week,3 months and 6 months after radiation therapy in the breast-conserving group and the radical resection group,there was no significant difference(all P>0.05),and the SWV of the sternocostal region of the affected side was significantly higher than that in the breast-conserving group at 1 week,3 months and 6 months after radiation therapy,and the difference was statistically significant(all P<0.05).Conclusion:1.SWE has high confidence in the quantitative evaluation of the elastic modulus of pectoralis major muscle in different parts of women,which shows that SWE can be an effective and non-invasive examination method for assessing muscle tissue stiffness.2.Postoperative radiotherapy results in increased pectoralis major muscle stiffness in the affected side of the clavicular and sternocostal region in breast cancer patients,and the hardness of the pectoralis major muscle increases with the time after radiation therapy.3.After radiotherapy with different surgical methods,the hardness of the pectoralis major muscle on the affected side was different,and the hardness of the clavicular region of the pectoralis major muscle on the affected side was not obvious after breast-conserving and radical resection radiotherapy,while the hardness of the sternocostal region of the pectoralis major muscle on the affected side was higher than that after breast-conserving surgery.4.Postoperative radiotherapy does not affect the stiffness of the pectoralis major muscle on the unaffected side of breast cancer patients.