Small airway dilation measured by endoscopic optical coherence tomography correlates with chronic lung allograft dysfunction

Abstract. Significance: Chronic lung allograft dysfunction (CLAD) is the leading cause of death in transplant patients who survive past the first year post-transplant. Current diagnosis is based on sustained decline in lung function; there is a need for tools that can identify CLAD onset. Aim: Endoscopic optical coherence tomography (OCT) can visualize structural changes in the small airways, which are of interest in CLAD progression. We aim to identify OCT features in the small airways of lung allografts that correlate with CLAD status. Approach: Imaging was conducted with an endoscopic rotary pullback OCT catheter during routine bronchoscopy procedures (n  =  54), collecting volumetric scans of three segmental airways per patient. Six features of interest were identified, and four blinded raters scored the dataset on the presence and intensity of each feature. Results: Airway dilation (AD) was the only feature found to significantly (p  <  0.003) correlate with CLAD diagnosis (R  =  0.40 to 0.61). AD could also be fairly consistently scored between raters (κinter-rater  =  0.48, κintra-rater  =  0.64). There is a stronger relationship between AD and the combined obstructive and restrictive (BOS + RAS) phenotypes than the obstructive-only (BOS) phenotype for two raters (R  =  0.92  ,  0.94). Conclusions: OCT examination of small AD shows potential as a diagnostic indicator for CLAD and CLAD phenotype and merits further exploration.