Airway Wall Thickness Assessed Using Computed Tomography and Optical Coherence Tomography

Abstract

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 FEV₁% 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 FEV₁. Conclusions: OCT can be used to measure airway wall dimensions. OCT may be more sensitive at detecting small airway wall changes that lead to FEV₁ changes in individuals with obstructive airway disease.