Abstract
Background: Chest computed tomography (CT) is an important tool to assess early cystic fibrosis (CF) structural lung disease, particularly early in life where no validated outcome measures exist. Current CF-CT scoring systems show poor agreement between observers in infants <3 yrs. CT scores must be reliable if they are to be validated as outcome measures.
Aim: To determine the repeatability of a quantitative scoring system for chest CT scans early in life.
Methods: Twenty-five volumetric CT scans from the AREST CF cohort obtained at age 1 or 3 yrs were scored by two observers using PRAGMA (Perth-Rotterdam Annotated Grid Morphometry Analysis). Briefly, a square grid was overlaid on 10 equidistant slices. Each cell was annotated according to whether it contained bronchiectasis, other abnormalities or healthy lung only, expressed as a proportion of the total lung for bronchiectasis (%Bx) or any lung abnormality (%Disease). This analysis was then repeated two months later by one observer. Repeatability was assessed using intraclass correlation coefficients (ICC).
Results: %Bx ranged from 0-3.9 (median 0.23) and %Disease ranged from 0-6.9 (median 1.04). ICCs for inter-observer reliability were 0.77 (good agreement) for %Bx and 0.65 (good agreement) for %Disease. For intra-observer reliability, ICCs were 0.79 (good agreement) for %Bx and 0.71 (good agreement) for %Disease.
Conclusion: Inter- and intra-observer agreement were high for PRAGMA, suggesting that this new method is more reliable in young children than the present gold standard. The biological relevance of this new scoring system will be further assessed in the AREST CF cohort by comparing outcomes with other markers of early CF lung disease.
- © 2014 ERS