A new method for determining the volume of fluid in the pleural cavity using computed tomography

Abstract

INTRODUCTION:Despite the existence of many methods and formulas for calculating the volume of pleural effusion in radiation diagnostics, there is still no single approved method for determining the volume of pleural effusion. Features of the anatomical structure of the chest and pleural cavity, the specific location of the effusion in this cavity and the need for a quick and easy way to calculate the volume of fluid in the pleural cavity determine the relevance of our study.OBJECTIVE:Based on the studied approved methods for calculating the volume of pleural fluid, propose a new method that takes into account the anatomical features of the form of the pleural effusion. Evaluate the results of the proposed methods, compare with the result of the most commonly used method at present.MATERIAL AND METHODS:The study included studies of 114 patients who underwent computed tomography of the chest cavity. The CT protocol was performed according to the standard program and included standard thin section reconstruction with a thickness of 0.625–1.25 mm with or without intravenous contrast. The results of the proposed method for calculating the volume of liquid were compared statistically with the volume of liquid obtained using the Simpson method. For volumes obtained, Bland-Altman plots were constructed, Wilcoxon criteria for related samples were determined, Spearman coefficients were calculated, and comparative volume plots were plotted with 95% confidence intervals.RESULTS:According to the results of statistical analysis, it was found that the average bias according to the Blunt-Altman method for the strip thickness formula was 51.5. The boundaries of the spread of values [463,7: –360]. For the ellipsoid difference method, the average bias was –0.6, the boundaries of the spread of values [187.3: –188.5].CONCLUSIONS.Calculating the volume of pleural fluid on CT remains one of the problems that does not have a single accurate method. The new ellipsoid volume difference method proposed by us showed high statistical results and showed an advantage over the «strip thickness» method.