To assess pulmonary abnormalities detected by high-resolution computed tomography (HRCT) in young children with cystic fibrosis (CF) and mild to moderate lung disease.

High-resolution computed tomography was performed in 60 children, 6 to 10 years old, with mild to moderate lung disease (forced expiratory volume in 1 minute [FEV₁], 52–137; mean, 102; SD, 15% predicted). HRCTs were scored by using a system that evaluates each lobe for severity and extent of CF lung disease. Findings of CF lung disease were tabulated in all subjects and in a subgroup with normal pulmonary function tests. HRCT scores were correlated with FEV₁, forced vital capacity (FVC), and forced expiratory flow between 25% and 75% of expired vital capacity (FEF_25-75) in 57 patients.

Bronchiectasis was present in 35% of subjects, mucous plugging in 15%, and air trapping in 63%. No abnormality was detected in 25%. In 37 subjects with FEV₁, FVC, and FEF_25-75 >85% predicted, bronchiectasis was present in 30%. In 17% of these subjects, bronchiectasis was seen in ≥4 lobes. Correlations between HRCT scores and FEV₁ were significant and showed fair to moderate correlation (r=0.36–0.46).

High-resolution computed tomography demonstrated a broad range of pulmonary abnormalities in young patients with CF with mild to moderate lung disease. In this study, abnormalities, including bronchiectasis, were common in young children with CF and normal pulmonary function tests.