Validation of human small airway measurements using endobronchial optical coherence tomography.

Background: Small airway remodeling is the cardinal feature underlying chronic airway diseases. There is no modality which identifies small airway pathological changes, which is crucial for early diagnosis, efficacy and prognostic assessment.

Objective: To evaluate the usefulness of endobronchial optical coherence tomography (EB-OCT) in assessing small airways morphology in vivo.

Methods: Twelve patients with pulmonary nodules scheduled for lung resection underwent spirometry, multi-detector computed tomography (MDCT) and EB-OCT. We measured D(mean) (mean luminal diameter), Ai (inner luminal area), Aw (airway wall area) and Aw% [Aw/(Ai + Aw) × 100%] from the 3rd to 5th generation bronchi of RB9 segment by MDCT. D(mean), Ai, Aw and Aw% from the 3rd to 9th generation bronchi of RB9 segment were measured by EB-OCT and histology. Correlations of these parameters, measured by three different methods, were evaluated. We recruited 4 COPD patients to determine if EB-OCT could identify peripheral airway remodeling.

Results: The 4 parameters, measured by CT and EB-OCT, correlated significantly [D(mean) (r = 0.991), Ai (r = 0.997), Aw (r = 0.997), Aw% (r = 0.991), all P < 0.01]. Significant correlation were found for these parameters, measured by histology and EB-OCT, from the 3rd to 5th generation bronchi [D(mean) (r = 0.989), Ai (r = 0.997), Aw (r = 0.999), Aw% (r = 0.988), all P < 0.01], and from the 6th to 9th generation bronchi [D(mean) (r = 0.979), Ai (r = 0.997), Aw (r = 0.994) and Aw% (r = 0.988), all P < 0.01]. Significant small airways morphological abnormalities were observed in COPD patients.

Conclusions: EB-OCT, a minimally invasive imaging modality with high-resolution, is useful and clinically practical for assessing proximal and distal airways of human compared with CT and histology.