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