Influence of airway pressure and fibrosis on lung surface shear wave elastography

Lung ultrasound is widely used in clinical practice, but B-mode findings often lack disease specificity. Shear wave elastography (SWE) enables quantitative assessment of tissue elasticity and may help overcome this limitation. This study aimed to evaluate whether SWE can be used to detect lung surface changes associated with airway pressure and pulmonary fibrosis.

Ex vivo porcine lungs (n = 3) were used to examine the effects of airway pressure. Airway pressure was adjusted to 10, 20, and 30 cmH₂O, and shear wave speed (SWS) was measured on the lung surface. Pulmonary fibrosis was induced in Sprague-Dawley rats (n = 13) by means of right thoracic irradiation. After 26 weeks, SWE was performed on excised lungs, and histopathological analysis of fibrosis and air proportions was conducted using QuPath-based image analysis. Statistical analyses included Spearman's correlation, Wilcoxon signed-rank test, and multiple regression with isometric log-ratio (ILR) transformation.

In porcine lungs, SWS increased with airway pressure and showed a strong positive correlation. In the radiation-induced fibrosis model, irradiated lungs had significantly higher SWS than non-irradiated lungs. Histopathology confirmed increased fibrosis and reduced air without inflammation. Multiple regression showed a significant association between fibrosis and SWS.

Lung surface SWE detected changes related to airway pressure and pulmonary fibrosis. SWS increased with both, although other factors, such as lung reduction in air content and tensile stress, can also affect measurements.