Utility of Elastography for Differentiating Malignant and Benign Lymph Nodes During EBUS-TBNA

Background: Ultrasound elastography noninvasively estimates tissue hardness. Studies have evaluated elastography for differentiating malignant from benign lymph nodes during endobronchial ultrasound-guided transbronchial needle aspiration. Several methods of performing elastography are described with variable diagnostic accuracy. Methods: The aim of this study was to evaluate endobronchial ultrasound-guided elastography in differentiating malignant from benign mediastinal lymphadenopathy. We performed a systematic search of the PubMed and Embase databases to extract the relevant studies. A diagnostic accuracy meta-analysis was carried out to calculate the pooled sensitivity and specificity [with 95% confidence intervals (CIs)], and positive and negative likelihood ratios of elastography. Results: After a systematic search, 20 studies (1600 patients, 2712 nodes) were selected. The pooled sensitivity and specificity of elastography were 0.90 (95% CI, 0.84-0.94) and 0.79 (95% CI, 0.73-0.84), respectively. The summary receiver operating curve demonstrated an area under the curve for elastography of 0.90 (0.88-0.93). The positive and negative likelihood ratios and the diagnostic odds ratio were 4.3 (95% CI, 3.3-5.5), 0.12 (95% CI, 0.07-0.20), and 35 (95% CI, 19-63), respectively. Of the most commonly described methods, the color classification method (type 3 malignant vs. type 1 benign) demonstrated the highest area under the curve of 0.91 (0.88-0.93). There was significant heterogeneity and publication bias. Subgroup analyses indicated no significant difference between the sensitivity and specificity of quantitative and qualitative elastography methods. Conclusions: Ultrasound elastography is useful in differentiating malignant and benign lymph nodes during endobronchial ultrasound-guided transbronchial needle aspiration. However, elastography does not replace the requirement of lymph node aspiration.