Quantitative CT lung volumetry and densitometry in pediatric pectus excavatum

The purpose of this study was to evaluate the quantitative computed tomography (CT) volumetry and densitometry and in pediatric patients with pectus excavatum (PE). We measured pectus index (PI) and separated inspiratory and expiratory lung volumes and densities. We obtained the total lung volume (TLV) and mean lung density (MLD) during inspiration and expiration, and the ratio of end expiratory to inspiratory volume (E/I volume) and MLD (E/I density) were calculated. The difference between inspiratory and end expiratory volume (I-E volume) and MLD (I-E density) were also calculated. A total of 199 patients, including 164 PE patients and 35 controls, were included in this study. The result shows that the PE group had lower inspiratory TLV (mean, 2670.76±1364.22 ml) than the control group (3219.57±1313.87 ml; p = 0.027). In the PE group, the inspiratory (-787.21±52.27 HU vs. -804.94±63.3 HU) and expiratory MLD (-704.51±55.41 HU vs. -675.83±64.62 HU) were significantly lower than the indices obtained from the control group (p = 0.006). In addition, significantly lower values of TLV and MLD difference and higher value of TLV and MLD ratio were found in the PE group (p <0.0001). PE patients were divided into severe vs. mild groups based on the PI cutoff value of 3.5. The inspiratory MLD and TLV ratio in the severe PE group were lower than those in the mild PE group, respectively (p <0.05). In conclusion, quantitative pulmonary evaluation through CT in pediatric PE patients may provide further information in assessing the functional changes in lung parenchyma as a result of chest wall deformity.