Two computed tomography (CT) quantitative analysis techniques demonstrated significant relationships with specific physiologic measures of small airway disease in patients with chronic obstructive pulmonary disease (COPD), according to study results published in the Annals of the American Thoracic Society.

Lung function measurements including peripheral airway resistance (R5-R19), peripheral airway reactance (AX), and acinar airway inhomogeneity (Sacin) from patients with COPD, never smokers, and healthy former smokers were measured by airway oscillometry and multiple breath nitrogen washout. Chest CT with parametric response mapping (PRM) and disease probability measure (DPM) analysis was used to compare measurements of small airway disease between groups.

Of the 79 participants included in the analysis, 38 had COPD, 18 were never smokers, and 23 were healthy former smokers. As expected, never smokers and healthy former smokers had preserved lung function. Participants with COPD had a median forced expiratory volume in 1 second of 71% predicted, with 29% classified as GOLD group 1 and 71% as GOLD group 2. R5-R19, AX, and Sacin were all significantly higher in participants with COPD compared with in never and healthy former smokers (P ≤.001).

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Analysis of CT scans showed significantly more emphysema and gas trapping in patients with COPD compared with never and healthy former smokers using either analysis method. However, there was significantly greater emphysema and gas trapping measured by DPM compared with PRM.

Emphysema and small airways disease are key pathological features of COPD, meaning it is vital that accurate methods for discriminating them are available,” They added, “T[hese] data demonstrate that these novel imaging techniques can detect subtle changes in lung structure to provide important phenotypical insights which could in the future be utilized for clinical and drug development purposes.”

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Ostridge K, Gove K, Paas KHW, et al. Using novel CT analysis to describe the contribution and distribution of emphysema and small airways disease in COPD [published March 20, 2019]. Ann Am Thorac Soc. doi:10.1513/AnnalsATS.201810-669OC