Alveolar Geometry Estimation Through Quantitative Lung Ultrasound Spectroscopy, Phantom Study with Monodisperse Vs Polydisperse Microbubble Populations

Lung ultrasound (LUS) is an imaging tool widely utilized to assess the state of the lung surface, which is nowadays primarily performed through the analysis of vertical artifacts (VAs), whose appearance correlates with pathologies characterized by air spaces’ reduction. As the VAs’ genesis seems to be associated with resonance phenomena occurring within the acoustic traps (ATs) formed along the pathological lung surface, a spectral characterization of VAs could indirectly estimate ATs’ dimensions and shape. In this study, for the first time, the correlation between the heterogeneity of ATs and VAs’ bandwidth was quantitatively and experimentally demonstrated. Specifically, lung-mimicking phantoms produced with monodisperse and polydisperse microbubble populations were used as samples. The results show how the monodisperse population has a significantly lower bandwidth than polydisperse population (median value is 3 MHz vs 6 MHz; one-way analysis of variance [ANOVA] p-value≈0.0006).