Diagnostic value of endobronchial ultrasound elastography for the differentiation of benign and malignant intrathoracic lymph nodes

Abstract

Introduction: Endobronchial ultrasound (EBUS) findings can be used to distinguish between benign and malignant lymph nodes (LNs). Recently, EBUS elastography has been introduced as a complementary modality in the evaluation of intrathoracic lymphadenopathy. Objective: To evaluate the ability of EBUS elastography to differentiate between benign and malignant LNs. Methods: A prospective study was conducted on the patients who were sent for evaluation of intrathoracic lymphadenopathy. LNs were classified qualitatively according to the elastographic color patterns: Type 1, predominantly non-blue; type 2, part blue, part non-blue; and type 3, predominantly blue. Quantitative elastography of LNs was measured by the strain ratio. Qualitative and quantitative elastography were compared with the final diagnosis of LNs. Results: There were 48 lymph nodes from 32 patients who underwent EBUS elastography. The final diagnosis included 34 malignant and 14 benign LNs. All of eight type 1 LNs were proved to be benign diseases, while 33 of 37 type 3 LNs were finally diagnosed as malignancy. Three LNs classified as type 2 were proved to be two benigns and one malignancy. Malignant LNs presented higher median strain ratio than benign LNs (29.3 vs 1.3, p=0.001). A strain ratio of more than 2.4 and non type 1 elastographic pattern achieved similar diagnostic performance in benign/malignant differentiation (sensitivity, 100% vs 100%; specificity, 71.4% vs 57.1%; PPV, 89.5% vs 85.0%; NPV, 100% vs 100%; AUC, 0.86 vs 0.79; p=0.14). Conclusion: EBUS elastography is a promising diagnostic modality for the differentiation between benign and malignant LNs.