Endobronchial polarization sensitive optical coherence tomography for airway wall imaging

Introduction: The gold standard to assess airway wall composition is by invasive focal biopsies. Endobronchial optical coherence tomography (EB-OCT) generates in vivo real-time high resolution images of the airways. Polarization sensitive OCT (EB-PS-OCT) provides tissue-specific contrast that enables airway smooth muscle (ASM) detection and quantification. Aim: Assess ASM content with PS-OCT in healthy and diseased airways. Methods: In vivo OCT imaging was performed in healthy volunteers, asthma and fibrotic interstitial lung diseases (fILD) patients. Standard OCT imaging was combined with PS-OCT birefringence and optical axis determination to detect, segment and quantify ASM. Results: 24 airways were imaged from distal to proximal (650-1000 cross-sectional images per airway) in 2 healthy volunteers, 2 asthma and 2 fILD patients. Standard OCT shows separate airway wall layers. PS-OCT enabled ASM segmentation in healthy and diseased airways (asthma and fILD). Preliminary results show an increase in ASM in diseased airways compared to healthy controls (Figure). Conclusion: Endobronchial PS-OCT is a minimally invasive imaging technique to identify airway wall layers with detection and quantification of ASM mass in both healthy and diseased airways. Implication: Endobronchial PS-OCT airway imaging is a promising tool to investigate airway wall remodeling in a minimally invasive way over full-length airway segments. ­­­