Expiratory Volumetric MDCT Evaluation of Air Trapping in Pediatric Patients With and Without Tracheomalacia

Abstract

The purpose of this study was to use paired inspiratory-expiratory volumetric MDCT to compare the frequency, severity, and pattern of air trapping in pediatric patients with tracheomalacia with the findings in children without tracheomalacia. The study group consisted of 15 consecutively registered pediatric patients (younger than 18 years) who had tracheomalacia, defined as 50% or greater reduction in tracheal cross-sectional luminal area between end inspiration and end expiration, diagnosed with MDCT and confirmed with bronchoscopy. The comparison group consisted of 15 consecutively registered pediatric patients without evidence of tracheomalacia at MDCT and bronchoscopy. Two blinded pediatric radiologists working in consensus interpreted the randomly viewed end-expiratory thin-section CT images of both groups of children for the presence, severity, and pattern of air trapping at three anatomic levels (upper, middle, and lower lung zones). The severity of air trapping was graded visually on a 5-point scale. The total air trapping scores, obtained by summing the values for the three anatomic levels for the study and comparison groups, were compared by Wilcoxon's rank sum test. The pattern of air trapping was categorized as lobular, segmental, lobar, diffuse, or mixed, and the patterns in the two study groups were compared by Pearson's chi-square test. The study cohort with tracheomalacia consisted of 15 patients (10 boys, five girls; mean age, 2.4 +/- 2.8 years; range, 1 month-11.8 years). The comparison group without tracheomalacia consisted of 15 patients (nine boys, six girls; mean age, 2.7 +/- 2.4 years; range, 1 month-8.1 years). Air trapping was identified in all 15 patients with tracheomalacia (median score, 5.0; range, 3-11) and in 10 of 15 children (67%) in the comparison group (median score, 3.0; range, 1-4). The median total air trapping score was significantly higher in the study cohort than in the comparison group (p = 0.002), but there were no significant differences in the air trapping patterns between the study groups (p = 0.53). Pediatric patients with tracheomalacia have a higher frequency and greater severity of air trapping than do children without tracheomalacia.