Geometric Validation of Continuous, Finely Sampled 3-D Reconstructions From aOCT and CT in Upper Airway Models

Identification and treatment of obstructive airway disorders (OADs) are greatly aided by imaging of the geometry of the airway lumen. Anatomical optical coherence tomography (aOCT) is a promising high-speed and minimally invasive endoscopic imaging modality for providing micrometer-resolution scans of the upper airway. Resistance to airflow in OADs is directly caused by the reduction in luminal cross-sectional area (CSA). It is hypothesized that aOCT can produce airway CSA measurements as accurate as that from computed tomography (CT). Scans of machine hollowed cylindrical tubes were used to develop methods for segmentation and measurement of airway lumen in CT and aOCT. Simulated scans of virtual cones were used to validate 3-D resampling and reconstruction methods in aOCT. Then, measurements of two segments of a 3-D printed pediatric airway phantom from aOCT and CT independently were compared to ground truth CSA. In continuous unobstructed regions, the mean CSA difference for each phantom segment was 2.2 ± 3.5 and 1.5 ± 5.3 mm2 for aOCT, and -3.4 ± 4.3 and -1.9 ± 1.2 mm2 for CT. Because of the similar magnitude of these differences, these results support the hypotheses and underscore the potential for aOCT as a viable alternative to CT in airway imaging, while offering greater potential to capture respiratory dynamics

Endoscopic, Anatomic OCT for Imaging and Compliance Measurement of Upper and Central Airways

Both acute airway injuries such as inhalation injury and prevalent but underdiagnosed diseases such as obstructive sleep apnea (OSA) lead not only to impaired quality of life but also to disability or even death. However, current techniques such as bronchoscopy, computed tomography and magnetic resonance imaging all have limitations, such as being semi-quantitative or the exposure to ionizing radiation or long scan times, when it comes to airway imaging. A modality that provides high-resolution, real-time, safe and minimally invasive imaging of the airways would be very beneficial in the diagnosis and treatment of airway diseases. Additionally, changes in the biomechanical properties of airway tissues associated with underlying pathophysiologic status of tissues have not been much explored. Thus, an imaging modality that also has the ability to perform elastography could be valuable in the diagnosis and treatment of inhalation injuries. Optical coherence tomography (OCT) is a rapidly developing imaging modality providing iv high-resolution and non-invasive imaging of tissue microstructure. To image the upper and central airways of pediatric patients, a specific type of OCT -- the swept-source anatomic optical coherence tomography (SSaOCT), which has a micron-level resolution and an imaging range over 10 mm is utilized. It allows direct visualization of features on airway walls as well as sub-surface structures such as cartilage and trachealis muscle. Moreover, aOCT together with a pressure catheter can be used to perform anatomic optical coherence elastography (aOCE) and measure airway compliance to predict the regions of the airway wall that are vulnerable to collapse. This provides additional diagnostic information of airways that is not easily achievable with other imaging modalities. In this dissertation, the design and performance of the two custom-built aOCT systems are described, and their ability to accurately measure airway geometry and compliance is investigated. Imaging of phantoms and animal specimens is performed, aOCE-derived compliance is calculated and the relationship between the compliance measurements and the severity of steam injury is evaluated. Results indicate that aOCT can perform accurate airway imaging as well as assess the compliance of airway tissues. The measured compliance of the airway could potentially be used as an index for grading and assessing the severity of injuries and thus aid in the diagnosis and treatment of airway inhalation injury.Doctor of Philosoph

Localized compliance measurement of the airway wall using anatomic optical coherence elastography

We describe an elastographic method to circumferentially-resolve airway wall compliance using endoscopic, anatomic optical coherence tomography (aOCT) combined with an intraluminal pressure catheter. The method was first demonstrated on notched silicone phantoms of known elastic modulus under respiratory ventilation, where localized compliance measurements were validated against those predicted by finite element modeling. Then, ex vivo porcine tracheas were scanned, and the pattern of compliance was found to be consistent with histological identification of the locations of (stiff) cartilage and (soft) muscle. This quantitative method may aid in diagnosis and monitoring of collapsible airway wall tissues in obstructive respiratory disorders

Sensing Inhalation Injury-Associated Changes in Airway Wall Compliance by Anatomic Optical Coherence Elastography

Quantitative methods for assessing the severity of inhalation (burn) injury are needed to aid in treatment decisions. We hypothesize that it is possible to assess the severity of injuries on the basis of differences in the compliance of the airway wall. Here, we demonstrate the use of a custom-built, endoscopic, anatomic optical coherence elastography (aOCE) system to measure airway wall compliance. The method was first validated using airway phantoms, then performed on ex vivo porcine tracheas under varying degrees of inhalation (steam) injury. A negative correlation between aOCE-derived compliance and severity of steam injuries is found, and spatially-resolved compliance maps reveal regional heterogeneity in airway properties

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