Abstract Rationale Recent research suggests that differences in airway caliber, assessed using high-resolution chest CT, may be a factor in the development of lung disease, with both increases and decreases possibly presaging worse outcomes. Quantitative computed tomography (qCT) measurements of airway tapering may provide a basis for robust analysis of airway caliber but have not been characterized in control populations to serve as a basis for comparison in disease populations. We sought to characterize associations between qCT-assessed airway tapering and anthropometry, pulmonary function, and other qCT metrics in healthy, non-smoking, control subjects. Methods Protocolized, thin-section, volumetric chest CT scans, collected as part of the COPDGene Project (NCT00608764) were analyzed using a fully automated qCT pipeline to produce metrics of airway volume, morphology, and tapering characteristics. Airway tapering was defined in terms of the homothety ratio, calculated as To calculate a subject-level value, the homothety ratio was average over all airway branches in generations 3-6, inclusive, with generation 3 representing segmental airways. Pulmonary function characteristics assessed were forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1), both as percent predicted. Other QCT metrics assessed were lung volume, airway tortuosity, airway volume, and airway wall thickness. Pearson correlation coefficients were used to assess the strength of association of the homothety ratio with the parameters described above, as well as height and age. An unpaired t-test was used to assess for differences between male and female subjects. Results 107 subjects were included, with a mean(SD) age of 62.3 (9.12) years. There were no differences in homothety ratio between men (n = 34) and women (n = 73). Homothety ratio was not associated with height, age at enrollment, lung volume, airway tortuosity, or airway wall thickness. Significant correlations were observed with FEV1 (r=-0.37, p 0.001), FVC (r=-0.36, p 0.001), and airway volume (r=-0.48, p 0.001), with lower homothety ratios (i.e. less tapering) associated with better pulmonary function and greater airway volume. Conclusions In healthy, non-smoking controls, the homothety ratio is not associated with height, age, sex, or lung volume. No association was observed with airway tortuosity or airway wall thickness. Subjects with greater airway tapering had worse pulmonary function and lower airway volumes. This suggests that homothety is a relatively stable metric within a population. Additional research with this metric in disease populations is underway. This abstract is funded by: None
Lavon et al. (Fri,) studied this question.