Quantitative Assessment of Pleural Sliding Velocity using Lung Ultrasound Spectroscopy: First Clinical Study on in-vivo Radio-Frequency Data

Lung ultrasound (LUS) data analysis is mainly limited to the visual interpretation of imaging patterns. A way to overcome this limitation is to develop quantitative approaches to assess these patterns. This study focuses on the quantification of pleural sliding by estimating its velocity (SlV ) on invivo radio-frequency (RF) data. Additionally, we assess the discriminating potential of SlV for cardiogenic pulmonary edema (CPE) and pneumonia. The analysis is carried out on a dataset of 102 RF multifrequency videos from 28 patients. The SlV estimation process is based on a novel velocity model, developed to estimate pixel velocities (v<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</inf>). The SlV is then estimated as the mean of v<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</inf> within the pleural line area. The estimated SlV showed values within the physiological range (≈0.75 mm/s - ≈4.00 mm/s). Finally, SlV values of the two populations were found to be statistically different, highlighting SlV potential in differentiating between CPE and pneumonia.