Airway wall thickness assessed using computed tomography and optical coherence tomography

Rationale: Computed tomography (CT) has been shown to reliably measure the airway wall dimensions of medium to large airways. Optical coherence tomography (OCT) is a promising new micron-scale resolution imaging technique that can image small airways 2 mm in diameter or less. Objectives: To correlate OCT measurements of airway dimensions with measurements assessed using CT scans and lung function. Methods: Forty-four current and former smokers received spirometry, CT scans, and OCT imaging at the time of bronchoscopy. Specific bronchial segments were identified and measured using the OCT images and three-dimensional reconstructions of the bronchial tree using CT. Measurements and Main Results: There was a strong correlation between CT and OCT measurements of lumen and wall area (r = 0.84, P < 0.001, and r = 0.89, P < 0.001, respectively). Compared with CT, OCT measurements were lower for both lumen and wall area by 31 and 66%, respectively. The correlation between FEV(1)% predicted and CT and OCT measured wall area (as percentage of the total area) of fifth-generation airways was very strong (r = -0.79, r = -0.75), but the slope of the relationship was much steeper using OCT than using CT (y = -0.33x + 82, y = -0.1x + 78), indicating greater sensitivity of OCT in detecting changes in wall measurements that relate to FEV(1). Conclusions: OCT can be used to measure airway wall dimensions. OCT may be more sensitive at detecting small airway wall changes that lead to FEV(1) changes in individuals with obstructive airway disease.