In pediatric patients with postinfectious bronchiolitis obliterans (PIBO), effective quantitative airway measurements and air-trapping evaluations based on chest computed tomography (CT) scans are technically feasible and correlate with pulmonary function tests (PFTs) in these individuals — specifically, wall area (WA) measurements in the airway and air-trapping volume (ATV).
These findings were from a retrospective study conducted in South Korea between January 2005 and December 2016 which were published in PLoS One.
Investigators sought to explore the practicality of using CT-based quantitative airway and air-trapping measurements, as well as to evaluate their association with PFTs, in children with PIBO. A quantitative analysis of segmental and subsegmental bronchi was performed on each chest CT scan, with areas or diameters of the walls, lumens, or the entire airway being calculated. The ATV in each lobe was also measured. Pearson or Spearman correlation was used to carry out comparison analyses between the CT parameters and PFT results.
A total of 23 patients with PIBO were enrolled in the study. The mean participant age was 7.0±3.3 years (range, 4-15 years). Overall, 89.6% of all segmental bronchi and 58.5% of subsegmental bronchi were successfully measured. Per airway analysis, WA demonstrated a negative correlation with forced expiratory volume in 1 second (FEV1) in the majority of the participants’ pulmonary lobes. Moreover, air-trapping analyses showed that ATV was negatively associated with FEV1 and positively associated with reactance at 5 Hz.
A major limitation of the study was that only 23 patients were examined because the researchers required a short amount of time between the CT and PFT in order to increase the validity of the correlation analysis. Also, since this was a retrospective study that evaluated previously collected data, this analysis was vulnerable to potential selection bias and to inconsistent CT scan protocols.
Nonetheless, the investigators concluded that the findings from this study imply potential clinical applications of quantitative CT scans to estimate the severity of disease in children with PIBO in whom PFT cannot be evaluated because of limited compliance.
Kim J, Kim M-J, Sol IS, et al. Quantitative CT and pulmonary function in children with post-infectious bronchiolitis obliterans. PLoS One. 2019;14(4):e0214647.