The radiologic definition of airway dilatation and bronchiectasis in children has substantial limitations. Bronchoarterial (BA) ratio is a commonly used criterion to define airway dilatation despite the lack of normative pediatric data. The objective of our study was to determine the range of normal bronchial to accompanying arterial diameter ratio on high-resolution CT scan of the chest in children and compare it with the available adult data.
Children undergoing multidetector CT scan of the chest for nonpulmonary conditions at a single center were prospectively identified. High-resolution reconstruction was performed on those included and both airway lumen and vessel diameters were measured in the upper and lower lobes of both lungs. Mean BA ratio was calculated for each included child, and its correlation with age was assessed.
Forty-one children were included; the mean (SD) BA ratio was 0.626 (0.068) (range, 0.437-0.739). This ratio was lower than comparable adult data (combined mean [SD], 0.676 [0.12]; P = .01). No correlation was found with age in our cohort (r = −0.21, P = .19). There was no difference in the ratio based on laterality or lobe.
In the pediatric age group, the airway is significantly smaller than the adjoining vessel. Using the radiologic criteria of BA ratio > 1 to define bronchial dilatation would underestimate the presence and extent of bronchiectasis, leading to delayed and missed diagnosis. This highlights the need to redefine the criteria for bronchial dilatation in children.