Lung density analysis using quantitative computed tomography in children with pectus excavatum

Introduction
To evaluate the mean lung density in children with pectus excavatum (PE) and to assess the correlation between the cardiac rotation angle, Haller index, pulmonary function test, and lung density.

Material and methods
This retrospective study included 33 children with PE and 31 healthy controls. The densities of lung parenchyma were evaluated by quantitative computed tomography (CT). Three lung levels were determined: T4 vertebra level, T10 vertebra level, and the level of the measurement of the cardiac rotation angle. The cardiac rotation angle and the Haller index were calculated. All measurements were done by 2 radiologists, independently. Student’s t-test or the Mann-Whitney U test, intraclass correlation coefficients, Pearson or Spearman’s rank correlation coefficient, and Kruskal-Wallis test were used for statistical analysis. A p-value less than 0.05 was considered as statistically significant.

Results
All the lung levels in the PE group had lower mean densities than healthy children, with statistical significance in the right lung at the T10 vertebra level (−818.60 ± 33.49 HU, −798.45 ± 40.24 HU; p = 0.028). There was a correlation between the cardiac rotation angle and the Haller index (ρ = 0.593; p < 0.001). There were no correlations between mean lung density and cardiac rotation angle, Haller index, and pulmonary function tests.

Conclusions
The lower mean lung densities were found in PE, especially in the right lower lobe. The parenchymal aeration should be considered independently from the severity of PE.