LAUSR

Asthma is a chronic inflammatory disease characterized by airway remodeling (AR), including thickening of airway smooth muscle (ASM) as a key element of this alteration. Patients with severe asthma may benefit from bronchial thermoplasty (BT), an endoscopic treatment that targets structural AR and induces ASM reduction. Assessment of AR is critical to evaluate the impact of BT and might provide a tool for patient selection for BT. Polarization sensitive optical coherence tomography (PS-OCT) imaging has been proposed as a minimally invasive diagnostic method to assess ASM mass as an alternative to focal airway biopsies. Bronchoscopic standard optical coherence tomography (OCT) is an imaging modality that generates highresolution cross-sectional images of the airways. PSOCT imaging provides tissue-specific contrast by assessing tissue birefringence, which enables ASM detection and quantification. The aim of this pilot study is to evaluate in vivo bronchoscopic PS-OCT imaging as a safe and minimally invasive, volumetric imaging technique to visualize and quantify ASM. To our knowledge, this is the first time an ASM reduction after BT was detected by PS-OCT imaging and a correlation between ASM mass in biopsies and in vivo PS-OCT images was found. Moreover, 3-dimensional (3D) volumetric reconstructions of ASM before and after BT are performed.