Assessment of early lung disease in young children with CF: A comparison between pressure-controlled and free-breathing chest computed tomography

BACKGROUND:
Chest computed tomography (CT) in children with cystic fibrosis (CF) is sensitive in detecting early airways disease. The pressure-controlled CT-protocol combines a total lung capacity scan (TLC PC-CT) with a near functional residual capacity scan (FRC PC-CT) under general anesthesia, while another CT-protocol is acquired during free breathing (FB-CT) near functional residual capacity. The aim of this study was to evaluate the sensitivity in detecting airways disease of both protocols in two cohorts.

METHODS:
Routine PC-CTs (Princess Margaret Children's Hospital) and FB-CTs (Erasmus MC-Sophia Children's Hospital) were retrospectively collected from CF children aged 2 to 6 years. Total airways disease (%disease), bronchiectasis (%Bx), and low attenuation regions (%LAR) were scored on CTs using the Perth-Rotterdam annotated grid morphometric analysis-CF method. The Wilcoxon signed-rank test was used for differences between TLC and FRC PC-CTs and the Wilcoxon rank-sum test for differences between FRC PC-CTs and FB-CTs.

RESULTS:
Fifty patients with PC-CTs (21 male, aged 2.5-5.5 years) and 42 patients with FB-CTs (26 male, aged 2.3-6.8 years) were included. %Disease was higher on TLC PC-CTs compared with FRC PC-CTs (median 4.51 vs 2.49; P < .001). %Disease and %Bx were not significantly different between TLC PC-CTs and FB-CTs (median 4.51% vs 3.75%; P = .143 and 0.52% vs 0.57%; P = .849). %Disease, %Bx, and %LAR were not significantly different between FRC PC-CTs and FB-CTs (median 2.49% vs 3.75%; P = .055, 0.54% vs 0.57%; P = .797, and 2.49% vs 1.53%; P = .448).

CONCLUSIONS:
Our data suggest that FRC PC-CTs are less sensitive than TLC PC-CTs and that FB-CTs have similar sensitivity to PC-CTs in detecting lung disease. FB-CTs seem to be a viable alternative for PC-CTs to track CF lung disease in young patients with CF.

Authors: Merel C. J. Oudraad, Wieying Kuo, Tim Rosenow, Eleni-Rosalina Andrinopoulou, Stephen M. Stick, Harm A. W. M. Tiddens. 

Published in Pediatric Pulmonology in March 2020.