Clinical Study On The Value Of Endobronchial Ultrasound Elastography In The Diagnosis Of Hilar And Mediastinal Lymph Nodes

Objective:Making correct diagnosis of hilar and mediastinal lymph nodes is key to the treatment of diseases. Endobronchial ultrasound elastography has been gradually used in clinic with the rapid development of ultrasonic technique, and presents a promising application prospect in differentiated diagnosis of benign and malignant lymph nodes. The study aimed to evaluate the role of endobronchial ultrasound elastography in the diagnosis of hilar and mediastinal lymph nodes and make synthetic evaluation for the value of conventional ultrasound and ultrasound elastography by using Logistic regression analysis.Methods:83 patients with 131 lesions under EBUS-TBNA were admitted in the study during October 2015 to March 2016 in bronchoscope center of the PLA General hospital. The ultrasonic diagnostic apparatus was EU-ME2 (Premier Plus) manufactured by Olympus company. Conventional ultrasound and ultrasound elastography were respectively used to examine 131 lymph nodes before aspiration, then the images were saved as video clips. Features of conventional ultrasound and parameters of ultrasound elastography were analysed and recorded by skilled worker. We defined the pathological results of EBUS-TBNA combined with results of six-month follow-up as the "Gold Standard". The ROC curves were drawn to obtain AUC and the best diagnostic threshold values of each parameters. According to the best cutoff values, we respectively calculated the accuracy, sensitivity, specificity, odds product of each parameters, and then compared them with each other to evaluate the value of ultrasound elastography. Logistic regression analysis was used to make synthetic evaluation for the value of conventional ultrasound and ultrasound elastography. Then we divided the lesions into groups according to their locations to further evaluate the value of area ratio and strain ratio of elastography.Results:1.The best cutoff value of area ratio to diagnose benign and malignant lymph nodes was 0.6,the AUC was 0.875, the accuracy, sensitivity, specificity were 84.43%,83.33%,86.00%.The diagnostic value was higher than that of conventional ultrasound features.2. The best cutoff value of strain ratio to diagnose benign and malignant lymph nodes was 14.33, the AUC was 0.882, the accuracy, sensitivity, specificity were 81.97%,81.94%,82.00%.The diagnostic value was higher than that of partial conventional ultrasound features.3. The AUC of elasticity score was 0.837, the accuracy, sensitivity, specificity were 83.61%,88.89%,76.00%.The diagnostic value was higher than that of partial conventional ultrasound features.4. The AUC and accuracy among area ratio, strain ratio, elasticity score had no significant difference, but the odds product of area ratio was higher than the others.5. There were five independent variables selected from Logistic regression analysis, including boundary, echo intensity, blood flow, short diameter and area ratio. The model could be used to predict these lesions. When the regression value P was more than 0.5, the prediction was malignant carcinoma, otherwise, the prediction was benign lesion. The accuracy, sensitivity, specificity were 91.80%,94.44%,88.00%, which were higher than that of features of conventional ultrasound and parameters of ultrasound elastography.6. After grouping, the diagnostic accuracy of area ratio was 90.08%, sensitivity was 89.87%,specificity was 90.38%, the diagnostic accuracy of strain ratio was 85.25%, sensitivity was 84.72%,specificity was 86.00%, these dates were higher than that before grouping, but the difference was not significant.Conclusions:1. area ratio, strain ratio, elasticity score of ultrasound elastography have high value in the differential diagnosis of hilar and mediastinal lymph nodes, and area ratio shows the highest comprehensive diagnostic capability.2. Five of ten independent variables are selected by Logistic regression analysis. The integration of conventional ultrasound and ultrasound elastography is beneficial to improve accuracy. 3. The diagnostic value is improved after grouping based on locations.