Ultrasound elastography for pneumothorax diagnosis: beyond the elasto-lung point

OBJETIVES: Ultrasound elastography is a promising non-invasive imaging technology that quantifies tissue elasticity. Only 2 studies have investigated ultrasound elastography for pneumothorax, both in strain elastography, reporting positive results and describing the novel elasto-lung point sign to aid in identifying the lung point. The objectives of this study are to confirm the existence of the elasto-lung point using 2-dimensional shear-wave elastography (2D-SWE), and to evaluate the utility of elastography in pneumothorax cases lacking a detectable lung point. METHODS: Prospective single-centre study of 32 consecutive patients with imaging-confirmed pneumothorax. The 2D-SWE measurements were collected from the pneumothorax area and the contralateral lung for comparative analysis. Ultrasound elastography was preferably performed during forced inspiration; when infeasible, measurements were collected during end-expiration or spontaneous breathing. RESULTS: The 2D-SWE measurements were collected primarily during spontaneous breathing (93.8%) and showed no significant differences in elasticity between pneumothorax and healthy lung. The lung point was detected in 14 patients, with the elasto-lung point identified in 13 (93% sensitivity; Cohen's Kappa = 0.936, P < .001). The 2D-SWE did not differentiate pneumothorax from healthy lung in absence of elasto-lung point. CONCLUSIONS: The 2D-SWE is a useful complement to ultrasound for detecting the lung point through visualization of the elasto-lung point. However, 2D-SWE could not distinguish pneumothorax from a healthy lung when the lung point was absent, contrasting with previously published results in strain elastography. ADVANCES IN KNOWLEDGE: This study confirms the existence of the elasto-lung point sign in 2D-SWE. However, 2D-SWE did not differentiate pneumothorax from healthy lung in absence of lung point.