Endobronchial Ultrasound Elastography for Diagnosing Mediastinal and Hilar Lymph Nodes

Abstract

Background:Pathophysiological processes, such as malignancy, can lead to the formation of stiffer tissue in lung cancers. Endobronchial ultrasound (EBUS) elastography is a novel technique for measuring tissue stiffness during EBUS-guided transbronchial needle aspiration (EBUS-TBNA). The current study was conducted to investigate the diagnostic value of EBUS elastography for mediastinal and hilar lymph node metastasis in lung cancers.Methods:From January 2014 to January 2015, 40 patients suspected of lung cancer were enrolled, and a total of 68 lymph nodes were evaluated by EBUS-TBNA. EBUS-guided elastography of lymph nodes was performed prior to EBUS-TBNA. Standard EBUS characteristics were also described. Pathological determination of malignant or benign lymph nodes was used as the gold standard for this study. If EBUS-TBNA did not result in a formal pathological diagnosis of malignancy, patients were referred for a surgical procedure. Comparisons of elastography and standard EBUS characteristics were made between benign and malignant lymph nodes.Results:Elastography grading scores and strain ratios showed significant differences between benign and malignant lymph nodes (P = 0.000). The elastography strain ratio was more sensitive and specific for determining malignant lymph nodes than elastography grading score or standard EBUS criteria. The receiver operating characteristic curve for the elastography strain ratio showed an area under the curve of 0.933. The best cut-off point of the strain ratio for differentiating malignant from benign lymph nodes was 32.07. The elastography strain ratio had a sensitivity of 88.1%, the specificity of 80.8%, positive predictive value of 88.1%, and negative predictive value of 80.8% for distinguishing malignant from benign nodes. The overall accuracy of elastography strain ratio was 85.3%. The strain ratio of malignant and benign lymph nodes positively correlated with the elastography grading score (r = 0.561, P = 0.000).Conclusions:EBUS elastography can be effectively used to predict mediastinal and hilar lymph node metastases in lung cancer. This noninvasive technique may thus complement standard EBUS and help guide EBUS-TBNA procedures.

Endobronchial Ultrasound Elastography Differentiates Intrathoracic Lymph Nodes: A Meta-Analysis

“…Whether the semiquantitative method or quantitative method is a better approach is still not clear. In the study by He and colleagues [17], the quantitative method of strain ratio showed a better diagnostic yield than the semiquantitative method of the elastography score. However, in the studies by Sun [19] and Huang [21] and their colleagues, the elastography score showed better performance than the quantitative method of mean grey value.…”

“…Our literature search yielded 36 publications for consideration, 29 of which were excluded for the following reasons: 10 were review articles or comments, two were case reports, three were not written in English, seven were a letter to editor or meeting abstract, and the seven were not specified (Fig 1). The remaining seven publications met all of the inclusion criteria and were included for this meta-analysis [10,11,[17][18][19][20][21].…”

“…Huang and colleagues [21] and Korrungruang and colleagues [20] adopted the similar classification method in their studies. However, He [17] and Sun [19] and their colleagues chose four or five types for classification [17,19]. In contrast to the semiquantitative methods, quantitative methods mostly relied on computer-aided calculation, and thereby overcame the bias of artificial judgments.…”

“…The quantitative methods, however, did not seem to be stable. For example, the strain ratio was chosen in the studies of He [17], Rozman [18], and Korrungruang [20] and their colleagues to describe the elastography images. Although their results were similar, the cutoff values for these three studies were 32.07, 8, and 2.5, respectively.…”

Estimation and validation of patient‐specific high‐resolution lung elasticity derived from 4DCT

“…A critical lung biomechanical property related to parenchymal tissue stiffness is the elastic modulus. Elastography is a noninvasive imaging technique for quantifying the elasticity distribution of the tissue . Currently, elastography techniques exist across several modalities including MR, ultrasound, and manual palpation .…”