Endobronchial Optical Coherence Tomography Research Articles

Microscopic Small Airway Abnormalities Identified in Early Idiopathic Pulmonary Fibrosis InVivo Using Endobronchial Optical Coherence Tomography.

Rationale: Idiopathic pulmonary fibrosis (IPF) affects the subpleural lung but is considered to spare small airways. Micro-computed tomography (micro-CT) studies demonstrated small airway reduction in end-stage IPF explanted lungs, raising questions about small airway involvement in early-stage disease. Endobronchial optical coherence tomography (EB-OCT) is a volumetric imaging modality that detects microscopic features from subpleural to proximal airways. Objectives: In this study, EB-OCT was used to evaluate small airways in early IPF and control subjects invivo. Methods: EB-OCT was performed in 12 subjects with IPF and 5 control subjects (matched by age, sex, smoking history, height, and body mass index). Subjects with IPF had early disease with mild restriction (FVC: 83.5% predicted), which was diagnosed per current guidelines and confirmed by surgical biopsy. EB-OCT volumetric imaging was acquired bronchoscopically in multiple, distinct, bilateral lung locations (total: 97 sites). IPF imaging sites were classified by severity into affected (all criteria for usual interstitial pneumonia present) and less affected (some but not all criteria for usual interstitial pneumonia present). Bronchiole count and small airway stereology metrics were measured for each EB-OCT imaging site. Measurements and Main Results: Compared with the number of bronchioles in control subjects (mean = 11.2/cm3; SD = 6.2), there was significant bronchiole reduction in subjects with IPF (42% loss; mean = 6.5/cm3; SD = 3.4; P = 0.0039), including in IPF affected (48% loss; mean: 5.8/cm3; SD: 2.8; P < 0.00001) and IPF less affected (33% loss; mean: 7.5/cm3; SD: 4.1; P = 0.024) sites. Stereology metrics showed that IPF-affected small airways were significantly larger, more distorted, and more irregular than in IPF-less affected sites and control subjects. IPF less affected and control airways were statistically indistinguishable for all stereology parameters (P = 0.36-1.0). Conclusions: EB-OCT demonstrated marked bronchiolar loss in early IPF (between 30% and 50%), even in areas minimally affected by disease, compared with matched control subjects. These findings support small airway disease as a feature of early IPF, providing novel insight into pathogenesis and potential therapeutic targets.

Endobronchial optical coherence tomography helps to estimate the cartilage damage of the central airway in TBTB patients.

At present, there are few examination methods used to evaluate tracheobronchial cartilage damage. In our study, we explored whether endobronchial optical coherence tomography (EB-OCT) can be used to estimate central airway cartilage damage in tracheobronchial tuberculosis (TBTB) patients. In our study, we used the OCTICS Imaging system to perform EB-OCT scanning for TBTB patients. The thickness of the central airway wall and cartilage was measured by the OCTICS software system workstation. There were 102 TBTB patients included in our study cohort. Their EB-OCT images of the central airway cartilage showed that abnormal cartilage manifests as thinning of the cartilage, cartilage damage, cartilage destruction, and even cartilage deficiency. The cartilage morphology becomes irregular and discontinuous. Some parts of the cartilage become brighter in grayscale. The intima of the cartilage is thickened and discontinuous, and the boundary with submucosa and mucosa is unclear. Our study conducted EB-OCT examination of the central airway cartilage of TBTB patients in vivo for the first time. EB-OCT helps to estimate the cartilage damage of the central airway in TBTB patients to some extent.

Endobronchial optical coherence tomography or computed tomography for evaluating progression of bronchiectasis.

The early radiological signs of progression in bronchiectasis remain unclear. The objective of the present study was to compare endobronchial optical coherence tomography (EB-OCT) and chest computed tomography (CT) for the evaluation of radiological progression of bronchiectasis via stratification of the presence (TW+) or absence (TW-) of thickened-walled bronchioles surrounding dilated bronchi in patients with bronchiectasis based on CT, and determine the risk factors. In this prospective cohort study, we performed both chest CT and EB-OCT at baseline and 5-year follow-up, to compare changes in airway calibre metrics. We evaluated bacterial microbiology, sputum matrix metalloproteinase-9 levels and free neutrophil elastase activity at baseline. We compared clinical characteristics and airway calibre metrics between the TW+ and TW- groups. We ascertained radiological progression at 5 years via CT and EB-OCT. We recruited 75 patients between 2014 and 2017. At baseline, EB-OCT metrics (mean luminal diameter (p=0.017), inner airway area (p=0.005) and airway wall area (p=0.009) of seventh- to ninth-generation bronchioles) were significantly greater in the TW+ group than in the TW-group. Meanwhile, EB-OCT did not reveal bronchiole dilatation (compared with the same segment of normal bronchioles) surrounding nondilated bronchi on CT in the TW- group. At 5 years, 53.1% of patients in the TW+ group progressed to have bronchiectasis measured with EB-OCT, compared with only 3.3% in TW- group (p<0.05). 34 patients in the TW+ group demonstrated marked dilatation of medium-sized and small airways. Higher baseline neutrophil elastase activity and TW+ bronchioles on CT predicted progression of bronchiectasis. Thickened-walled bronchioles surrounding the dilated bronchi, identified with EB-OCT, indicates progression of bronchiectasis.

Novel diagnostic techniques in interstitial lung disease.

Research into novel diagnostic techniques and targeted therapeutics in interstitial lung disease (ILD) is moving the field toward increased precision and improved patient outcomes. An array of molecular techniques, machine learning approaches and other innovative methods including electronic nose technology and endobronchial optical coherence tomography are promising tools with potential to increase diagnostic accuracy. This review provides a comprehensive overview of the current evidence regarding evolving diagnostic methods in ILD and to consider their future role in routine clinical care.

EB-OCT: a potential strategy on early diagnosis and treatment for lung cancer.

Lung cancer is the leading cause of cancer-related death in China and the world, mainly attributed to delayed diagnosis, given that currently available early screening strategies exhibit limited value. Endobronchial optical coherence tomography (EB-OCT) has the characteristics of non-invasiveness, accuracy, and repeatability. Importantly, the combination of EB-OCT with existing technologies represents a potential approach for early screening and diagnosis. In this review, we introduce the structure and strengths of EB-OCT. Furthermore, we provide a comprehensive overview of the application of EB-OCT on early screening and diagnosis of lung cancer from in vivo experiments to clinical studies, including differential diagnosis of airway lesions, early screening for lung cancer, lung nodules, lymph node biopsy and localization and palliative treatment of lung cancer. Moreover, the bottlenecks and difficulties in developing and popularizing EB-OCT for diagnosis and treatment during clinical practice are analyzed. The characteristics of OCT images of normal and cancerous lung tissues were in good agreement with the results of pathology, which could be used to judge the nature of lung lesions in real time. In addition, EB-OCT can be used as an assistant to biopsy of pulmonary nodules and improve the success rate of biopsy. EB-OCT also plays an auxiliary role in the treatment of lung cancer. In conclusion, EB-OCT is non-invasive, safe and accurate in real-time. It is of great significance in the diagnosis of lung cancer and suitable for clinical application and is expected to become an important diagnostic method for lung cancer in the future.

The role of tracheal wall injury in the development of benign airway stenosis in rabbits

To investigate the role of tracheal wall injury in the development of benign airway stenosis in rabbits. Prospective study. We injured the tracheal walls of 28 New Zealand white rabbits using four different methods. Experimental group: Group A (n = 7, mild injury of tracheal mucosa by ordinary brush under bronchoscopy); Group B (n = 7, severe injury of tracheal mucosa by nylon brush under tracheotomy); Group C (n = 7, tracheal cartilage was injured by vascular clamp after tracheotomy); Group D (n = 7, the tracheal cartilage was injured with vascular forceps and the tracheal mucosa was injured with a nylon brush after tracheotomy). Bronchoscopy was performed on each experimental rabbit at 1, 2, 3 and 4 weeks after operation. High-resolution computed tomography (HRCT) and endobronchial optical coherence tomography (EB-OCT) were performed at 4 weeks, and the rabbits were sacrificed after the examination. Their gross and histological findings were comparatively determined whether the experimental rabbit stenosis was established. No airway stenosis was observed in group A. In group B, 28.57% of experimental rabbits developed tracheal stenosis (granulation tissue proliferation was observed in rabbits No. 2 and No. 6 at 1, 2 and 3 weeks after operation, and the tracheal scar contracture was observed in No.6 rabbit at 4 weeks after operation). Fourteen rabbits in group C and group D had tracheal stenosis caused by granulation tissue proliferation at 1, 2 and 3 weeks after operation. At the fourth week after operation, 71.43% of experimental rabbits had tracheal stenosis due to granulation tissue hyperplasia, 7.14% of experimental rabbits had tracheal stenosis due to scar contracture and granulation hyperplasia, and 21.43% of experimental rabbits had tracheal stenosis due to scar contracture. EB-OCT scan showed that the cartilage layer with low signal reflection band was discontinuous. The injury of cartilage is the key factor of benign airway stenosis. Acute injury of airway mucosa alone is unlikely to cause airway stenosis, but combined with cartilage injury may aggravate airway stenosis. EB-OCT can clearly identify the airway layers of rabbits, which is helpful to evaluate the damage of tracheal cartilage and mucosa. The diagnostic potential of this technique makes EB-OCT a promising approach for the study and monitoring of airway diseases.

Deep Learning-Based Segmentation of Airway Morphology from Endobronchial Optical Coherence Tomography

Background: Manual measurement of endobronchial optical coherence tomography (EB-OCT) images means a heavy workload in the clinical practice, which can also introduce bias if the subjective opinions of doctors are involved. Objective: We aim to develop a convolutional neural network (CNN)-based EB-OCT image analysis algorithm to automatically identify and measure EB-OCT parameters of airway morphology. Methods: The ResUNet, MultiResUNet, and Siamese network were used for analyzing airway inner area (Ai), airway wall area (Aw), airway wall area percentage (Aw%), and airway bifurcate segmentation obtained from EB-OCT imaging, respectively. The accuracy of the automatic segmentations was verified by comparing with manual measurements. Results: Thirty-three patients who were diagnosed with asthma (n = 13), chronic obstructive pulmonary disease (COPD, n = 13), and normal airway (n = 7) were enrolled. EB-OCT was performed in RB9 segment (lateral basal segment of the right lower lobe), and a total of 17,820 OCT images were collected for CNN training, validation, and testing. After training, the Ai, Aw, and airway bifurcate were readily identified in both normal airway and airways of asthma and COPD. The ResUNet and the MultiResUNet resulted in a mean dice similarity coefficient of 0.97 and 0.95 for Ai and Aw segmentation. The accuracy Siamese network in identifying airway bifurcate was 96.6%. Bland-Altman analysis indicated there was a negligible bias between manual and CNN measurements for Ai (bias = −0.02 to 0.01, 95% CI = −0.12 to 0.14) and Aw% (bias = −0.06 to 0.12, 95% CI = −1.98 to 2.14). Conclusion: EB-OCT imaging in conjunction with ResUNet, MultiResUNet, and Siamese network could automatically measure normal and diseased airway structure with an accurate performance.

Airway morphological abnormalities of bronchiolitis assessed by endobronchial optical coherence tomography.

A few studies have reported the medium-sized and small airway morphological abnormalities of bronchiolitis. Whether spirometry or impulse oscillometry (IOS) is correlated with airway remodeling of bronchiolitis remains unclear. Aiming to demonstrate the airway morphological abnormalities of bronchiolitis obliterans (BO) and diffuse panbronchiolitis (DPB) assessed by endobronchial optical coherence tomography (EB-OCT), and elucidate whether spirometric and IOS parameters have correlation with the airway remodeling of bronchiolitis. We recruited 18 patients with bronchiolitis (BO, n = 9; DPB, n = 9) and 17 control subjects. Assessments of clinical features, St. George's respiratory questionnaire (SGRQ), chest computed tomography (CT), spirometry, IOS, and EB-OCT were performed in all enrolled subjects. The correlation between EB-OCT and lung function parameters was studied and analyzed. The magnitude of abnormalities of spirometric and IOS parameters was significantly greater in patients with bronchiolitis than that in control subjects (p < 0.05). Patients with BO had notably lower forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC, maximal mid-expiratory flow (MMEF)% pred and higher resonant frequency (Fres), and area of reactance (AX) than those with DPB (p < 0.05). The EB-OCT measurement among patients with bronchiolitis and between the bronchus in the left and the right lung demonstrated a heterogeneous distribution of airway calibers, presenting a high intra- and inter-individual variability. Patients with bronchiolitis had notably greater airway wall area (p < 0.05) compared with control, while BO presented greater magnitude of airway abnormalities than DPB. Fres and the difference in airway resistance at 5 and 20 Hz (R5-R20) correlated negatively with medium-sized and small airway inner area, and correlated positively with airway wall area (p < 0.05), whose correlation coefficients were higher than those of spirometric parameters. Bronchiolitis, BO and DPB, manifested a heterogeneous distribution of airway calibers with significant intra- and inter-individual variability. IOS parameters, rather than spirometry, correlated better with medium-sized and small airway remodeling in bronchiolitis assessed by EB-OCT measurement.

E-Cigarette Use, Small Airway Fibrosis, and Constrictive Bronchiolitis

BackgroundVaping, including the use of electronic cigarettes (e-cigarettes), has become increasingly prevalent, yet the associated long-term health risks are largely unknown. Given the prevalence of use, particularly among adolescents early in their lifespan, it is vital to understand the potential chronic pathologic sequelae of vaping.MethodsWe present the cases of four patients with chronic lung disease associated with e-cigarette use characterized by clinical evaluation, with pulmonary function tests (PFTs), chest high-resolution computed tomography (HRCT), endobronchial optical coherence tomography (EB-OCT) imaging, and histopathologic assessment.ResultsEach patient presented with shortness of breath and chest pain in association with a 3- to 8-year history of e-cigarette use, with mild progressive airway obstruction on PFTs and/or chest HRCT findings demonstrating evidence of air trapping and bronchial wall thickening. EB-OCT imaging performed in two patients showed small airway–centered fibrosis with bronchiolar narrowing and lumen irregularities. The predominant histopathologic feature on surgical lung biopsy was small airway–centered fibrosis, including constrictive bronchiolitis and MUC5AC overexpression in all patients. Patients who ceased vaping had a partial, but not complete, reversal of disease over 1 to 4 years.ConclusionsAfter thorough evaluation for other potential etiologies, vaping was considered to be the most likely common causal etiology for all patients due to the temporal association of symptomatic chronic lung disease with e-cigarette use and partial improvement in symptoms after e-cigarette cessation. In this series, we associate the histopathologic pattern of small airway–centered fibrosis, including constrictive bronchiolitis, with vaping, potentially defining a clinical and pathologic entity associated with e-cigarette use. (Funded in part by the National Institutes of Health.)

Optical coherence tomography for identification of malignant pulmonary nodules based on random forest machine learning algorithm.

ObjectiveTo explore the feasibility of using random forest (RF) machine learning algorithm in assessing normal and malignant peripheral pulmonary nodules based on in vivo endobronchial optical coherence tomography (EB-OCT).MethodsA total of 31 patients with pulmonary nodules were admitted to Department of Respiratory Medicine, Zhongda Hospital, Southeast University, and underwent chest CT, EB-OCT and biopsy. Attenuation coefficient and up to 56 different image features were extracted from A-line and B-scan of 1703 EB-OCT images. Attenuation coefficient and 29 image features with significant p-values were used to analyze the differences between normal and malignant samples. A RF classifier was trained using 70% images as training set, while 30% images were included in the testing set. The accuracy of the automated classification was validated by clinically proven pathological results.ResultsAttenuation coefficient and 29 image features were found to present different properties with significant p-values between normal and malignant EB-OCT images. The RF algorithm successfully classified the malignant pulmonary nodules with sensitivity, specificity, and accuracy of 90.41%, 77.87% and 83.51% respectively.ConclusionIt is clinically practical to distinguish the nature of pulmonary nodules by integrating EB-OCT imaging with automated machine learning algorithm. Diagnosis of malignant pulmonary nodules by analyzing quantitative features from EB-OCT images could be a potentially powerful way for early detection of lung cancer.

A clinical and canine experimental study in small-airway response to bronchial thermoplasty: Role of the neuronal effect

BackgroundThe effects of bronchial thermoplasty (BT) on smooth muscle (SM) and nerves in small airways are unclear. MethodsWe recruited 15 patients with severe refractory asthma, who received BT treatment. Endobronchial optical-coherence tomography (EB-OCT) was performed at baseline, 3 weeks' follow-up and 2 years' follow-up to evaluate the effect of BT on airway structure. In addition, we divided 12 healthy beagles into a sham group and a BT group, the latter receiving BT on large airways (inner diameter >3 mm) of the lower lobe. The dogs’ lung lobes were resected to evaluate histological and neuronal changes of the treated large airways and untreated small airways 12 weeks after BT. ResultsPatients receiving BT treatment had significant improvement in Asthma Control Questionnaire (ACQ) scores and significant reduction in asthma exacerbations. EB-OCT results demonstrated a notable increase in inner-airway area (Ai) and decrease in airway wall area percentage (Aw%) in both large (3rd-to 6th-generation) and small (7th-to 9th-generation) airways. Furthermore, the animal study showed a significant reduction in the amount of SM in BT-treated large airways but not in untreated small airways. Protein gene product 9.5 (PGP9.5)–positive nerves and muscarinic receptor 3 (M3 receptor) expression in large and small airways were both markedly decreased throughout the airway wall 12 weeks after BT treatment. ConclusionsBT significantly reduced nerves, but not SM, in small airways, which might shed light on the mechanism of lung denervation by BT.

Postintubation Tracheal Stenosis Evaluated by Endobronchial Optical Coherence Tomography: A Canine Model Study

Background: The predictors and airway morphological changes during the development of postintubation tracheal stenosis (PITS) have not been well elucidated. Objectives: To elucidate the validation of endobronchial optical coherence tomography (EB-OCT) in assessing the airway morphological changes in PITS. Methods: We performed oral endotracheal intubation in 12 beagles to establish the PITS model. EB-OCT was performed respectively before modeling and on the 1st, 7th, and 12th day after extubation in 9 canines, and was conducted consecutively in 3 canines during the development of PITS. Histological findings and the thickness and gray-scale value of the tracheal wall assessed by EB-OCT measurements were analyzed and compared. Results: The tracheal wall edema, granulation tissue proliferation, cartilage destruction in PITS, and airway wall thickening detected by EB-OCT were in concordance with the histopathological measurements. The consecutive EB-OCT observation of the airway structure demonstrated the tracheal wall thickness significantly increased from 344.41 ± 44.19 μm before modeling to 796.67 ± 49.75 μm on the 9th day after modeling (p < 0.05). The airway wall gray-scale values assessed by EB-OCT decreased from 111.19 ± 14.71 before modeling to 74.96 ± 4.08 on the 9th day after modeling (p < 0.05). The gray-scale value was negatively correlated with the airway wall thickness (r = –0.945, p = 0.001). Conclusion: The EB-OCT imaging, in concordance with the histopathological finding, was validated for assessing the airway morphological changes during the development of PITS. The EB-OCT evaluation of cartilage damage and gray-scale value measurement might help predict the development and prognosis of PITS.

Airway Remodeling and Bronchodilator Responses in Asthma Accessed by Endobronchial Optical Coherence Tomography

Background: Asthma is characterized by chronic airway inflammation and remodeling. Understanding airway structural changes and the bronchodilator responses may help unravel targets for intervention. However, structural abnormalities of asthmatic airways with different disease severity and the major anatomical site of bronchodilator responses have not been well elucidated. Methods: We recruited 104 asthmatic patients (when clinically stable) and 31 non-smoking control subjects to compare the airway inner area (Ai) and airway wall area percentage (Aw%) with endobronchial optical coherence tomography. We also enrolled 32 patients with moderate-to-severe asthma to dynamically access the airway morphological changes after salbutamol inhalation. Findings: More prominent airway structural abnormalities correlated with greater asthma severity, evidenced by the decreased Ai and greater Aw% in medium-sized and small airways. Patients with mild asthma yielded comparable Ai but greater Aw% than control subjects. A longer disease duration correlated with lower Ai and greater Aw% from the 3rd to 6th generation of bronchi. Salbutamol inhalation led to a rapid dilatation of both medium-sized and small airways, the lung function improvement correlated significantly with the increase in Ai of the medium-sized, but not small, airways at 15 min. Interpretation: Luminal narrowing and airway wall thickening of the medium-sized and small airways are present in mild asthma and reflect asthma severity, lending support to the use of anti-imflammatory intervention in mild asthma. The medium-sized airways are the crucial site of the bronchodilator responses, providing the scientific rationale for future development of more effective delivery of inhaled medications for asthma. Funding Statement: National Natural Science Foundation of China (No.81770017), National Natural Science Foundation of China (No.81900032), Pearl River S&T Nova Program of Guangzhou No. 201710010097 and Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme 2017 Declaration of Interests: Prof. Li declared that he had received the National Natural Science Foundation of China (No.81770017). Dr Su declared that he had received the National Natural Science Foundation of China (No.81900032). Prof. Guan declared that he had received Pearl River S&T Nova Program of Guangzhou No. 201710010097, and Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme 2017. All other authors declared no potential conflict of interest. None of the funding sources had any role on the study Ethics Approval Statement: This study was approved by the Ethics Committee of The First Affiliated Hospital of Guangzhou Medical University (Medical Ethics [Year 2014] No. 51 and [Year 2019] No. K09). All subjects gave written informed consent.

Evaluation of the Normal Airway Morphology Using Optical Coherence Tomography

The anatomic location of small airways, the distribution of airway cartilage, and their correlation with ageing have not been well elucidated. The objective of this article was to explore the morphologic characteristics of small airways invivo, and how airway structural changes correlate with age using endobronchial optical coherence tomography (EB-OCT). We recruited 112 subjects with peripheral pulmonary nodules. Participants underwent CT scan, spirometry, and EB-OCT measurements. We measured the airway internal diameter, the inner area (Ai), the airway wall area percentage (Aw%), and the thickness of airway cartilage. EB-OCT airway structural characteristics at different age intervals were analyzed, and the association between airway morphology and age was evaluated. Of the small airways, 47.3%originated from the seventh generation of bronchi. Cartilage was uniformly present in the third to sixth generation of bronchi, despite a decreasing proportion of cartilage from the seventh to ninth generation of bronchi (92.4%, 54.5%, and 26.8%, respectively). The thickness of airway cartilage progressively decreased with older age. In subjects 40 to 54 years of age, Ai from the third to sixth generation correlated positively with age (r= 0.577, P< .001). Both Aifrom the third to sixth generation and Ai from the seventh to ninth generation correlated negatively with age in subjects 55 to 69 years of age (r=-0.374, P= .021 and r=-0.410, P= .011). Aw%from the third to sixth generation and Aw%from the seventh to ninth generation did not correlate significantly with age. Small airways are mainly located at the seventh generation, where cartilaginous structures are present despite reduced distribution in more distal airways, and the thickness decreased in older age. Reduction in luminal area of medium-to-small airways might be the morphologic changes associated with ageing (ie, > 55 years of age).

Quantitative assessment of airway remodelling and response to allergen in asthma.

In vivo evaluation of the microstructural differences between asthmatic and non-asthmatic airways and their functional consequences is relevant to understanding and, potentially, treating asthma. In this study, we use endobronchial optical coherence tomography to investigate how allergic airways with asthma differ from allergic non-asthmatic airways in baseline microstructure and in response to allergen challenge. A total of 45 subjects completed the study, including 20 allergic, mildly asthmatic individuals, 22 non-asthmatic allergic controls and 3 healthy controls. A 3-cm airway segment in the right middle and right upper lobe were imaged in each subject immediately before and 24 h following segmental allergen challenge to the right middle lobe. Relationships between optical airway measurements (epithelial and mucosal thicknesses, mucosal buckling and mucus) and airway obstruction (FEV1 /FVC (forced expiratory volume in 1 s/forced vital capacity) and FEV1 % (FEV1 as a percentage of predictive value)) were investigated. Significant increases at baseline and in response to allergen were observed for all four of our imaging metrics in the asthmatic airways compared to the non-asthmatic airways. Epithelial thickness and mucosal buckling exhibited a significant relationship to FEV1 /FVC in the asthmatic group. Simultaneous assessments of airway microstructure, buckling and mucus revealed both structural and functional differences between the mildly asthmatic and control groups, with airway buckling seeming to be the most relevant factor. The results of this study demonstrate that a comprehensive, microstructural approach to assessing the airways may be important in future asthma studies as well as in the monitoring and treatment of asthma.

Automated segmentation and quantification of airway mucus with endobronchial optical coherence tomography.

We propose a novel suite of algorithms for automatically segmenting the airway lumen and mucus in endobronchial optical coherence tomography (OCT) data sets, as well as a novel approach for quantifying the contents of the mucus. Mucus and lumen were segmented using a robust, multi-stage algorithm that requires only minimal input regarding sheath geometry. The algorithm performance was highly accurate in a wide range of airway and noise conditions. Mucus was classified using mean backscattering intensity and grey level co-occurrence matrix (GLCM) statistics. We evaluated our techniques in vivo in asthmatic and non-asthmatic volunteers.

Automated segmentation and quantification of airway mucus with endobronchial optical coherence tomography

Automated segmentation and quantification of airway mucus with endobronchial optical coherence tomography

Measuring Airway Remodeling in Patients With Different COPD Staging Using Endobronchial Optical Coherence Tomography

Although FEV1 remains the gold standard for staging COPD, the association between airway remodeling and airflow limitation remains unclear. Endobronchial optical coherence tomography (EB-OCT) was performed to assess the association between disorders of large and medium to small airways and COPD staging. We also evaluated small airway architecture in heavy smokers with normal FEV1 (SNL) and healthy never-smokers. We recruited 48 patients with COPD (stage I, n= 14; stage II, n= 15; stage, III-IV, n= 19), 21 SNL, and 17 healthy never-smokers. A smoking history inquiry, as well as spirometry, chest CT, bronchoscopy, and EB-OCT were performed. Mean luminal diameter (Dmean), inner luminal area (Ai), and airway wall area (Aw) of third- to ninth-generation bronchi were measured using EB-OCT. Patients with more advanced COPD demonstrated greater abnormality of airway architecture in both large and medium to small airways, followed by SNL and never-smokers. Abnormality of airway architecture and EB-OCT parameters in SNL were comparable to those in stage I COPD. FEV1%predicted correlated with Dmean and Ai of seventh- to ninth-generation bronchi in COPD; however, neither Dmean nor Ai of third- to sixth-generation bronchi correlated with FEV1%in stage I and stage II COPD and in SNL. FEV1-based COPD staging partially correlates with small airway disorders instage II-IV COPD. Small airway abnormalities detected by EB-OCT correlate with FEV1-based staging in COPD and identify early pathologic changes in healthy heavy smokers.

Value of Endobronchial Optical Coherence Tomography in Identifying Small Airway Remodeling in Patients With COPD

Value of Endobronchial Optical Coherence Tomography in Identifying Small Airway Remodeling in Patients With COPD

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

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.