Clinical Value Of Shear Wave Elastography In Evaluating The Elasticity Of Salivary Glands Before And After Radiotherapy For Nasopharyngeal Carcinoma

Objective:1.The aim of this observational study was to investigate the clinical value of Shear Wave Elastography(SWE)in evaluating salivary gland elasticity changes and two-dimensional sonographic features before and after radiotherapy,to evaluate the feasibility and clinical value of SWE technique in evaluating the changes of salivary gland elasticity before and after radiotherapy for nasopharyngeal carcinoma.2.To analyze correlation between glandular tissue elasticity and the extent of xerostomia after radiotherapy.Materials and methods:Forty-six patients with nasopharyngeal carcinoma(NPC)treated in our oncology department from March 2018 to October 2019 were selected,patients ranged in age from 30 to 70 years old.Ultrasound examination was performed on all patients before radiotherapy(S0),4 weeks after radiotherapy(S1),6 weeks after radiotherapy(S2),3 months after radiotherapy(S3),and 6 months after radiotherapy(S4),12 months after radiotherapy(S5),the echogenicity and homogeneity of salivary gland tissues(parotid and submandibular glands)were evaluated by two-dimensional ultrasound,then the young's modulus values were measured by SWE,and the differences of two-dimensional ultrasonic manifestations and young's modulus between the six groups were compared.The extent of xerostomia was evaluated referring to radiation reaction of RTOG/EORTC during S3 and S5.Results:1.Among the 46 patients included in this study,5 of them were unwilling to continue to receive ultrasound examination due to unbearable neck pain caused by radiotherapy,and 1 of them lost follow-up.Finally,40 patients successfully completed the whole radiotherapy and follow-up process.2.Compared with S0,S1,S2,S3,S4 and S5,there were statistically significant differences in the echogenicity and homogeneity of salivary gland tissues(p <0.05).3.Compared with S0,S1,S2,S3,S4 and S5,the young's modulus values were statistically different(p <0.05);There was no significant difference in young's modulus between the left and right sides of salivary glands at different stages of radiotherapy(p >0.05).Before radiotherapy,there were no statistically significant differences in young's modulus values of parotid glands and submandibular glands among different sex groups,height groups and weight groups(p >0.05).There was no statistically significant difference between left and right young's modulus values at different radiotherapy stages(p>0.05).4.There was no significant correlation between the elasticity of parotid and submandibular glands and the the extent of xerostomia.Conclusion:1.Radiotherapy for nasopharyngeal carcinoma can cause some changes in the echogenicity and homogeneity of salivary gland tissues.2.At different stages of radiotherapy,young's modulus of salivary gland tissue was independent of lateral,sex,height and weight.3.SWE can evaluate the changes of glandular stiffness before and after radiotherapy.During radiotherapy,the elastic values of glandular tissues did not increase significantly.With the extension of time,the elastic value of glands gradually increased,and the degree of fibrosis gradually worsened,and there was no significant correlation between the elasticity of glands and the the extent of xerostomia.The technique can diagnose the severity of glandular fibrosis after radiotherapy and provide an effective evidence for early clinical intervention and treatment.4.SWE technology has high clinical application value because of its advantages of noninvasive,simple and repeatable.