Small airway dilation visualized by optical coherence tomography (OCT) correlates with the diagnosis of chronic lung allograft dysfunction (CLAD)

Abstract

Background: Small airways and the surrounding tissue of the lung allograft are often affected by pathological processes including acute cellular rejection (ACR), infections and different phenotypes of CLAD. OCT with superior resolution but shallow penetration, allows the visualization of these structures in contrast to routine radiographic imaging.

Methods: We studied 54 lung transplant (LTx) recipients with OCT imaging during surveillance (n=36) or event (n=19) bronchoscopies. Volumetric images of 3 segmental airways were collected from each patient. OCT features were scored by 4 raters blinded to the clinical status of LTx recipients. Pearson correlation coefficients (R) were used to determine the relation between OCT features and the presence of ACR, infection or CLAD diagnosis. Diagnostic potential was assessed by rater reliability using Fleiss’ Kappa (κ) and receiver operating characteristic (ROC) analysis.

Results: Among 54 recipients 21/54 were imaged < 1 year and 34/54 ≥ 1 year post-LTx, 9/54 met diagnostic criteria for CLAD. Observed OCT features were loss of alveolar visualization, emphysema-like alveolar enlargement, alveolar hyperinflation, airway dilation, excessive mucous, excessive duct-like structures, and an unidentified structure. Airway dilation was significantly associated (p<0.002) with CLAD diagnosis R=0.40-0.61 and κ=0.37. ROC curves resulted in areas under curves 0.69-0.85. No OCT features were significantly correlated with the presence of ACR or infection.

Conclusions: OCT imaging may identify the presence of CLAD by small airway dilation and may be employed as an early and sensitive diagnostic tool.