Optical coherence tomography (OCT) of chronic lung allograft dysfunction (CLAD)

This study explores endobronchial optical coherence tomography (OCT) imaging of lung transplant patients with chronic lung allograft dysfunction (CLAD). Optical coherence tomography (OCT), the optical analog of ultrasonography with superior resolution (10μm) but shallow (2mm) penetration, allows for the visualization of the early structural changes in the small airways, which is of interest in CLAD progression.Imaging was conducted with a catheter-based rotary OCT probe during routine bronchoscopy procedures, resulting in three-dimension pullbacks of three subsegmental airways per patient (n=9). A scoring rubric for visualized features of interest was used to quantify characteristics of the image set: loss of alveolar visualization, emphysema-like alveolar enlargement, alveolar hyperinflation, airway dilation, excessive mucous, excessive duct-like structures, and an unidentified structure. Four raters, blinded to clinical status, scored the set. Statistical analysis including Pearson correlation coefficients (R), Fleiss’ Kappa (κ) were used on this score set to assess preliminary potential of these features.3/9 patients met the diagnostic criteria for both obstructive (BOS) and restrictive (RAS) phenotypes of CLAD and 6/9 for solely the obstructive phenotype. The airway dilation feature was found to be significantly associated (p<0.05) with the BOS+RAS diagnosis for three raters (R=0.72-0.94), with fairly consistent rater reliability (κinterrater = 0.25, κintrarater = 0.59). No OCT features were significantly correlated with infection status.Small airway dilation, as measured through catheterized OCT imaging, shows potential for use in detection of CLAD and distinguishing between CLAD phenotypes.