Validation of human small-airway measurements using endobronchial optical coherence tomography: an observational study

Abstract

BackgroundSmall-airway remodelling is the cardinal pathological feature underlying chronic obstructive pulmonary disease (COPD). Identification of early-stage pathological changes is crucial for the diagnosis, treatment, and prognosis of respiratory diseases. Our study aimed to investigate the usefulness of endobronchial optical coherence tomography (EB-OCT) in assessment of small-airways morphology in patients with pulmonary nodules who were scheduled for lung resection surgery (four had COPD, four were smokers with normal lung function, and four were life-long non-smokers). Patients with respiratory diseases other than COPD were excluded. Methods12 patients with pulmonary nodules scheduled for lung resection underwent spirometry, multidetector CT (MDCT), and EB-OCT. We measured mean luminal diameter (Dmean), inner luminal area (Ai), airway wall area (Aw), and Aw% [Aw/(Ai+Aw)×100%] from the third to fifth generation bronchi of RB9 segment by MDCT. Dmean, Ai, Aw, and Aw% from the third to nineth generation bronchi of RB9 segment were measured by EB-OCT and histology. The correlations of these four parameters, measured by MDCT, EB-OCT, and histology, were studied. The study protocol was approved by the ethics committee of the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China, and written informed consent was obtained before the study. This study was registered with the Chinese Clinical Trial Register, number ChiCTR-DOD-14005734. FindingsEB-OCT was well tolerated. The four parameters measured by CT correlated significantly with their respective parameters measured by EB-OCT (Dmean r=0·991, Ai r=0·997, Aw r=0·997, Aw% r=0·991; all p<0·0001). Significant correlations were noted between the four parameters measured by histology and their respective parameters measured by EB-OCT from the third to fifth-generation bronchi (Dmean r=0·989 [p<0·0001], Ai r=0·997 [p<0·0001], Aw r=0·999 [p=0·003], Aw% r=0·988 [p=0.001]) and from the sixth to nineth-generation bronchi (Dmean r=0·979, Ai r=0·997, Aw r=0·994, Aw% r=0·988; all p<0·0001). Substantial morphological small-airways abnormalities were observed in patients with COPD. InterpretationEB-OCT, a direct and minimally invasive imaging modality with high resolution, is useful for assessment of proximal and distal airways compared with CT (for larger airways) and histology. FundingNone.