[Value of endobronchial ultrasound elastography in the diagnosis of mediastinal and hilar lymph node metastasis in lung cancer].

OBJECTIVE: To assess the value of endobronchial ultrasound elastography in the diagnosis of mediastinal and hilar lymph node metastasis in lung cancer. 


METHODS: A total of 40 patients with lung cancer underwent ultrasonic bronchoscope examination before operation. Elastography and standard endobronchial ultrasound (EBUS) of lymph nodes were performed before EBUS-guided transbronchial needle aspiration (EBUS-TBNA). The elastography characteristics was compared between benign and malignant lymph nodes. The diagnosis accuracy in malignant lymph nodes was also compared between the elastography and the standard EBUS. The value of the elastography was assessed in distinguishing the benign and malignant lymph nodes.


RESULTS: 1) The significant indicators of standard EBUS in diagnosis of malignant lymph nodes were hypoechonic nodes, uneven echo, distinct boundary and short diameter greater than 1 cm (all P<0.01). 2) There was significant difference in the elastosonography grading score between benign and malignant lymph nodes (P<0.01). 3) The elastography grading score was more sensitive and specific in determining the malignant lymph node than the standard EBUS criteria. The area under the receiver operating characteristic curve (AUC) was maximal when the elastography grading score was ≥2.5. The specificity, sensitivity, positive predictive value, negative predictive value of elastography grading score was 76.9%, 85.7%, 85.7% and 76.9% in distinguishing malignant and benign nodes. The overall accuracy of elastography grading score was 82.3%. The combination of elastography grading score, low echo, distinct boundary and short diameter greater than 1 cm showed the best diagnostic efficiency value. The AUC was 0.911. In distinguishing malignant and benign nodes, the specificity, sensitivity, positive predictive value, negative predictive value and accuracy of the combined indexes was 84.6%, 88.1%, 90.2%, and 81.5% respectively. The overall accuracy was 86.8%.


CONCLUSION: The endobronchial ultrasound elastography can effectively distinguish the mediastinal and hilar lymph node metastasis in lung cancer. The diagnosis accuracy of elastography in malignant lymph node is higher than that of standard EBUS criteria. The combination of elastosonography grading score and standard EBUS criteria can improve the diagnostic efficiency.