Correlation between quantitative computed tomography analysis and pulmonary function in children with post-infectious bronchiolitis obliterans

Abstract

Purpose: To investigate the availability of computed tomography (CT) based quantitative airway and emphysema measurements and to assess their correlation with pulmonary function in children with post-infectious bronchiolitis obliterans (PIBO). Materials and Methods: This retrospective study included chest CT scans and pulmonary function tests (PFT) completed between January 2005 and December 2016 on children diagnosed with PIBO. The quantitative analysis of segmental and subsegmental bronchi was performed on each chest CT scan. The emphysema volume (EV), the volume of lung area exhibiting lower attenuation than the mean attenuation of normal and air trapping areas, was also measured in each lobe. The ratio between EV and total lung volume (emphysema ratio, ER) was then calculated. The PFT values included spirometric parameters and impulse oscillometric parameters. Comparison analyses between CT parameters and PFT results were made with Pearson or Spearman. Results: In total 23 patients were enrolled (age 7.0 ± 3.3 years – range, 4-15 years). We successfully measured 371 (371/414, 89.6%) segmental and 242 (242/414, 58.5%) subsegmental bronchi. In airway analysis, wall area showed negative correlation with forced expiratory volume in one second (FEV1) in the majority of the pulmonary lobes. The airway average diameter and airway area were also negatively correlated with FEV1 in bilateral lower lobes. Emphysema analyses demonstrated that EV was negatively correlated with FEV1 and positively correlated with an oscillometric parameter, reactance at 5 Hz. Conclusion: Quantitative airway and emphysema measurements from chest CT are feasible and can demonstrate pulmonary function in pediatric PIBO patients.