Endobronchial Ultrasound Strain Elastography in Sarcoidosis

Overview

Strain elastography (SE) is an imaging method used for the measurement of relative tissue elasticity through qualitative (color pattern) or semi-quantitative methods (strain ratio or strain histogram). Very recently, the first pilot study has provided preliminary evidence that EBUS-SE elastography may help identify fibrotic lymph nodes in sarcoidosis and that sampling lymph nodes characterized by low strain elastography, that is "stiff" nodes, is associated with an increased risk of retrieving an inadequate sample (i.e. a sample which is not representative of the lymph node tissue). The investigators hypothesize that an EBUS-SE pattern indicative of lymph node stiffness will be associated with less granulomas and more fibrosis.

In the last decade, the possibility to sample under ultrasound guidance (endosonography) the intrathoracic lymph nodes through the airways (endobronchial ultrasound guided, EBUS-TBNA) or through the oesophagus (endoscopic ultrasound-guided fine needle aspiration, EUS-FNA/EUS-b-FNA) has revolutionized the diagnostic approach to sarcoidosis. Individual studies and meta-analyses performed in selected and unselected patient populations have shown that EBUS and EUS both have overall diagnostic accuracy exceeding 80%. In addition, endosonography provides useful information about lymph node density; indeed, the presence of inhomogeneity in the lymph node texture on B-mode during endosonography represents the most important factor favouring infection over sarcoidosis in patients with lymphadenopathy. Although the diagnostic success rate of EBUS-TBNA in detecting granulomas in lymph nodes of patients with suspected sarcoidosis is very high, the procedure is not foolproof and tends to have a lower yield in stages II/III as compared to stage I disease. Clinical experience suggests that at least some of the false-negative EBUS-TBNA results in sarcoidosis patients may be caused by the presence of lymph nodes with extensive fibrosis. We aim to evaluate whether EBUS-SE may help identify fibrotic lymph nodes in sarcoidosis and if the outcome of EBUS-TBNA is different in lymph nodes for which EBUS-SE suggest high fibrotic content.

Conditions