A95-06 New Microscopic Honeycombing Detected by Serial Endobronchial Optical Coherence Tomography Is Predictive of Progression in IPF

Rationale Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease with variable clinical courses amongst individual patients. With the growing availability of therapeutic options, early accurate monitoring of disease is essential for optimizing management. While HRCT and PFT are standard tests for serial monitoring, their limited resolution and sensitivity hinder early detection of disease progression. Endobronchial optical coherence tomography (EB-OCT) is a safe, minimally-invasive, repeatable bronchoscope-based technique that provides rapid, high-resolution (∼10um), volumetric imaging at multiple sites in the bilateral lungs, potentially enabling detection of early disease changes. We assessed serial EB-OCT imaging to detect microscopic disease progression in IPF. Methods IPF subjects were recruited to undergo two timepoint bronchoscopy under conscious sedation with EB-OCT imaging, spaced ∼6 months apart. PFT and HRCT were acquired concurrently at both timepoints, and subsequently as part of clinical follow-up. EB-OCT was performed in ∼10 sites/subject at baseline, and repeat imaging was performed at the same sites using airway branchpoint mapping. For each site, EB-OCT features were evaluated by consensus among three EB-OCT experts, including microscopic honeycombing, traction bronchiolectasis, fibrosis, and microprogression. HRCT was independently evaluated by a thoracic radiologist. EB-OCT and HRCT were qualitatively compared across corresponding subsegments. Subject-level disease progression was defined as two or more of the following: (1) FVC ≥10% or DLCO ≥15% decline within 1 year; (2) HRCT progression in multiple sites; (3) worsening respiratory symptoms. Results Ten subjects were included in this analysis. A total of 100 sites were imaged; 20 were excluded due to insufficient distal positioning or imaging artifact. Of the remaining 80 sites, 62 (77.5%) had matched imaging locations across the two timepoints. At baseline, EB-OCT identified microscopic honeycombing in all 10 subjects (66% of sites), while HRCT detected honeycombing in 5 subjects (24.5% of sites). Seven subjects met criteria for progression: 3 progressed over the two EB-OCT imaging timepoints (6-months) and 4 progressed on follow-up over 1-3 years later. Three subjects remained stable without progression for ≥24 months. Two timepoint EB-OCT detected newly developed multifocal honeycombing in all subjects with progression. Subjects with stable disease had at most mild progression changes detected by EB-OCT, without presence of multifocal new honeycombing. Kaplan-Meier curves show progression outcome divergence between subjects with and without new multifocal honeycombing detected by EB-OCT (Figure 1). Conclusion EB-OCT is a safe, repeatable, minimally-invasive imaging modality with the potential to detect early disease progression beyond the capabilities of HRCT and PFT.