Air trapping in early cystic fibrosis lung disease-Does CT tell the full story?
INTRODUCTION
Mosaic attenuation on expiratory chest computed tomography (CT) is common in early life cystic fibrosis (CF) and often referred to as "air trapping". It is presumed to be localized hyperinflation due to small airway obstruction. In order to test this assumption, we compared air trapping extent to lung volumes measured on CT in young children with CF.


MATERIALS AND METHODS
Children aged below 7 years undergoing inspiratory/expiratory CT were recruited from the Australian Respiratory Early Surveillance Team for Cystic Fibrosis cohort. Automated lung segmentation was used to determine functional residual capacity (FRC), total lung capacity (TLC), and their ratio (FRC/TLC). Structural lung disease (%Disease) and air trapping (%TrappedAir) extent were assessed using PRAGMA-CF. Lung clearance index (LCI), an index of ventilation heterogeneity, was measured. Linear mixed model analysis was used to determine associations.


RESULTS
Seventy-three scans from 55 patients were obtained. %TrappedAir was associated with %Disease (0.19 [0.07, 0.31]; P = 0.003) and LCI (0.22 [0.04, 0.39]; P = 0.016), but not FRC/TLC (0.00 [-0.02, 0.02]; P = 0.931).


DISCUSSION
CT mosaic attenuation is associated with CF lung disease, however it is not always accompanied by physiologic hyperinflation. Other pathologies may contribute to mosaic attenuation. A better understanding of these factors could guide future therapies.
['Rosenow|Tim|T|0000-0003-3727-5131', 'Ramsey|Kathryn|K|', 'Turkovic|Lidija|L|', 'Murray|Conor P|CP|', 'Mok|L Clara|LC|', 'Hall|Graham L|GL|', 'Stick|Stephen M|SM|', '|||']
D001315:Australia D002648:Child D002675:Child, Preschool D003550:Cystic Fibrosis D005260:Female D005652:Functional Residual Capacity D006801:Humans D007223:Infant D016014:Linear Models D008168:Lung D008297:Male D014057:Tomography, X-Ray Computed D014109:Total Lung Capacity
air trapping computed tomography cystic fibrosis (CF) imaging paediatrics