Estimation of pleural effusion volume through chest ultrasound: validation of two multiplanar models

Computed tomography (CT) scanning is the gold standard when estimating pleural effusion volume; however, the procedure exposes patients to ionizing radiation. Our study was aimed at developing ultrasound-based calculation models that can quantify the volume of pleural effusion in seated patients and validating each model using volumetric chest CT analyses as reference. Our study enrolled 36 hospitalized patients who underwent a chest CT scan and ultrasound, in the seated position, with the aid of a convex probe. To estimate the volume of pleural effusions, we applied one linear and two multiplanar ultrasound-based equations using a CT reconstruction as reference. Testing these models in our validation set (n = 16), we determined that 0.42 was the R2 coefficient for the linear equation, and 0.97 and 0.98, respectively, were the R2 coefficients for the cylindrical-sector models, and observed that the latter had the lowest dispersion of data and an optimal intraclass correlation coefficient. We then concluded that multiplanar ultrasound-based equations are accurate and reliable in estimating pleural effusions and outperform previously developed equations.