Children with severe asthma have substantial structural airway changes on computed tomography.

Background: In adults with severe asthma (SA) bronchial wall thickening, bronchiectasis and low attenuation regions (LAR) have been described on chest computed tomography (CT) scans. The extent to which these structural abnormalities are present in children with SA is largely unknown. Our aim was to study the presence and extent of airway abnormalities on chest CT of children with SA.
Methods: 161 inspiratory and expiratory CT scans, either spirometer-controlled or technician-controlled, obtained in 131 children with SA (mean±SD age 11.0±3.8 years) were collected retrospectively. Inspiratory scans were analysed manually using a semi-quantitative score and automatically using LungQ (v2.1.0.1; Thirona B.V., Nijmegen, the Netherlands). LungQ segments the bronchial tree, identifies the generation for each bronchus-artery (BA) pair and measures the following BA dimensions: outer bronchial wall diameter (B _out ), adjacent artery diameter (A) and bronchial wall thickness (B _wt ). Bronchiectasis was defined as B _out /A ≥1.1, bronchial wall thickening as B _wt /A ≥0.14. LAR, reflecting small airways disease (SAD), was measured automatically on inspiratory and expiratory scans and manually on expiratory scans. Functional SAD was defined as FEF _25-75 and/or FEF ₇₅ z-scores <-1.645. Results are shown as median and interquartile range.
Results: Bronchiectasis was present on 95.8% and bronchial wall thickening on all CTs using the automated method. Bronchiectasis was present on 28% and bronchial wall thickening on 88.8% of the CTs using the manual semi-quantitative analysis. The percentage of BA pairs defined as bronchiectasis was 24.62% (12.7-39.3%) and bronchial wall thickening was 41.7% (24.0-79.8%) per CT using the automated method. LAR was observed on all CTs using the automatic analysis and on 82.9% using the manual semi-quantitative analysis. Patients with LAR or functional SAD had more thickened bronchi than patients without.
Conclusion: Despite a large discrepancy between the automated and the manual semi-quantitative analysis, bronchiectasis and bronchial wall thickening are present on most CT scans of children with SA. SAD is related to bronchial wall thickening.
Competing Interests: Conflict of interest: W.B. van den Bosch reports an unconditional research grant for a PhD from Vectura Group PLC during the conduct of the study (contract was signed in 2018 for the duration of 4 years). Conflict of interest: Q. Lv and E-R. Andrinopoulou have nothing to disclose. Conflict of interest: M.W.H. Pijnenburg reports support from Sanofi and Novartis outside the submitted work. Conflict of interest: P. Ciet reports personal fees from Vertex, Chiesi Pharmaceuticals BV and Editamed SRL, and grants from the Dutch Research Council, outside the submitted work. Conflict of interest: H.M. Janssens reports grants and other support from Vertex Pharmaceuticals outside the submitted work. Conflict of interest: H.A.W.M. Tiddens reports personal fees from Thirona BV during the conduct of the study; and grants and other support from Novartis, personal fees from Vertex and Insmed, and grants from Vectura Group PLC, outside the submitted work. In addition, H.A.W.M. Tiddens has a patent for the PRAGMA-CF scoring system licensed and Sophia Research BV of the Erasmus MC–Sophia Children's Hospital has, in the past 3 years received unconditional research grants from Novartis and Vectura Group PLC, research grants from IMI, CFF, ECFS and the Sophia Foundation, and honoraria and travel expenses for lectures and participation on expert panels from Novartis, Insmed and Vertex. He heads the Erasmus MC core laboratory LungAnalysis which is a not-for-profit core image analysis laboratory. The financial aspects of the laboratory are handled by Erasmus MC.
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