Joseph C. Jing, Khodayar Goshtasbi, Yong Wang, Jason J. Chen, Erica Su, Ellen M. Hong, Katelyn D. Dilley, Yan Li, Frances B. Lazarow, Anthony Chin Loy, David Shamouelian, Said E. Elghobashi, Zhongping Chen, Brian J. F. Wong
IntroductionThere are important limitations to the current diagnostic tools for obstructive sleep apnea (OSA). This warrants the development of a more accurate, minimally invasive, and objective tool to better characterize upper airway airflow obstruction during sleep.MethodsSwept-source optical coherence tomography (OCT) as a range-finding technique was utilized for upper airway volumetric reconstruction. An acousto-optic modulator was integrated into the OCT system for extending the imaging range to be suitable for the typical diameter of the upper airway. High spatial resolution images were acquired at 25 frames/s and translated at 12.5 mm/s before manual segmentation for three-dimensional (3D) reconstruction and numerical analysis. The Lattice-Boltzmann method as a computational fluid dynamics (CFD) technique was utilized to pinpoint the precise locations of turbulent airflow in the airspace.ResultsUpper airway OCT imaging of a 28-year-old individual with sleep disorder breathing was obtained during awake and sleep periods. The volumetric structure and 3D reconstruction of the upper airway through a micrometer-resolution optical imaging approach were successfully demonstrated. Cross-sectional volumetric changes from awake to sleep periods were calculated, and the greatest airway obstruction was observed at the level of the oropharynx. In addition to CFD analysis, measuring airflow pressure differences along the upper airway aided in accurately localizing the dominant sites of obstruction during sleep.ConclusionThe combination of the proposed OCT imaging system with 3D remodeling and CFD analysis led to accurate reconstruction of the upper airway and identification of obstruction sites during sleep. This technology can improve surgical decision-making and outcomes in OSA.
Spectrally encoded interferometric microscopy (SEIM) is capable of detecting nanometer displacement at a frame rate in the kilohertz regime. By employing a wavelength-sweeping laser and a spectral disperser, SEIM can achieve en face imaging via one-axis scanning. In this study, we compared different processing algorithms for visualizing cilia-induced motion. Our Doppler-based method, combined with phase stabilization and bulk motion correction, provides the highest sensitivity for measuring ciliary beating frequency amongst the tested methods. Traveling waves induced by coordinated cilia motion were visualized. These results demonstrate the potential clinical utility of SEIM for monitoring respiratory function and therapeutic effects.
Phase stability of an optical coherence elastography (OCE) system is the key determining factor for precision elasticity measurement. In this study, we developed an OCE system based on swept-source optical coherence tomography (SS-OCT) with a common-path configuration (SS-OCECP). Our system has a phase stability of 4.2 mrad without external stabilization or extensive post-processing, such as averaging. This phase stability allows us to detect a displacement as small as ~300 pm. We validated the SS-OCECP performance in a tissue-mimicking phantom and an in vivo rabbit model, and the results demonstrated significant improved phase stability compared to conventional SS-OCE. To the best of our knowledge, we demonstrated the first SS-OCECP system, which possess high phase stability and can be utilized to significantly improve the sensitivity of elastography.
Endoscopic optical coherence tomography (OCT) and near-infrared (NIR) fluorescence imaging system was developed for characterization of colorectal cancer (CRC). NIR fluorescence is able to highlight the cancer-suspected area based on significant change of tumor vascular density and morphology. Co-registered OCT images has the capability of visualizing subsurface tissue layer architecture, so the suspected regions can be further investigated by the altered light scattering resulted from the morphological abnormality. The imaging result from in vivo rat experiment has demonstrated the enhanced capability of identification and classification of CRC compared to using any of these technologies alone, thus has the potential to provide a new clinical tool to advance gastroenterology practice.
KEYWORDS: In vivo imaging, Cornea, Crystals, Coherence (optics), Elastography, Acoustics, Eye, Imaging systems, Eye models, Human vision and color perception
The changes in biomechanical properties of lens and cornea are closely correlated with presbyopia and cataract. We developed an optical coherence elastography system utilizing acoustic radiation force excitation to simultaneously assess the elasticities of the crystalline lens and the cornea in vivo. A swept light source was integrated into the system to provide an enhanced imaging range that covers both the lens and the cornea. Additionally, the oblique imaging approach combined with orthogonal excitation also improved the image quality. Simultaneous elasticity measurements of lens and cornea were performed in anesthetized rabbits to demonstrate the capability of ARF-OCE to characterize in vivo elasticity in the anterior eye.
Subglottic stenosis (SGS) is a challenging disease to diagnose in neonates. Long-range optical coherence tomography (OCT) is an optical imaging modality that has been described to image the subglottis in intubated neonates. A major challenge associated with OCT imaging is the lack of an automated method for image analysis and micrometry of large volumes of data that are acquired with each airway scan (1 to 2 Gb). We developed a tissue segmentation algorithm that identifies, measures, and conducts image analysis on tissue layers within the mucosa and submucosa and compared these automated tissue measurements with manual tracings. We noted small but statistically significant differences in thickness measurements of the mucosa and submucosa layers in the larynx (p < 0.001), subglottis (p = 0.015), and trachea (p = 0.012). The automated algorithm was also shown to be over 8 times faster than the manual approach. Moderate Pearson correlations were found between different tissue texture parameters and the patient’s gestational age at birth, age in days, duration of intubation, and differences with age (mean age 17 days). Automated OCT data analysis is necessary in the diagnosis and monitoring of SGS, as it can provide vital information about the airway in real time and aid clinicians in making management decisions for intubated neonates.
Subglottic stenosis is a severe and challenging disease to manage in neonates. Previous reports describe the usage of long-range optical coherence tomography (LR-OCT) to image the subglottis through an endotracheal tube and potentially identify subepithelial changes in subglottic mucosa which are correlated with edema or scar tissue. A major challenge associated with OCT imaging is that large volumes of data (1-2 GB) are acquired with each airway scan, with no existing automated method for image analysis and tissue measurement. We have developed an innovative MATLAB based auto-segmentation program which identifies and measures tissue layers within the mucosa. LR-OCT data sets of 21 neonates were analyzed for mucosal thickness of the proximal trachea, subglottis and larynx. The auto-segmentation measurements were compared with measurements from manual tracings by a single operator. We found statistically significant associations between the thickness of the mucosa (p<0.001) and submucosa (p<0.001) layers in the upper airway when comparing these two segmentation processes. The auto-segmentation program segmented the OCT images on average over 8 times faster than the manual segmentation software. Following auto-segmentation, OCT images were also analyzed for texture analysis properties using ANOVA. Automated segmentation and measurement of OCT data sets is an efficient and precise method to analyze large volume LR-OCT data stacks. This may ultimately help provide vital objective information about the airway in real-time, which would aid clinicians in making management decisions for intubated neonates.
Ciliated epithelial cells populate up to 80% of the surface area of the human airway and are responsible for
mucociliary transport, which is the key protective mechanism that provides the first line of defense in the respiratory
tract. Cilia beat in a rhythmic pattern and may be easily affected by allergens, pollutants, and pathogens, altering ciliary
beat frequency (CBF) subsequently. Diseases including cystic fibrosis, chronic obstructive pulmonary disease, and
primary ciliary dyskinesia may also decrease CBF. CBF is therefore a critical component of respiratory health. The
current clinical method of measuring CBF is phase-contrast microscopy, which involves a tissue biopsy obtained via
brushing of the nasal cavity. While this method is minimally invasive, the tissue sample must be oriented to display its
profile view, making the visualization of a single layer of cilia challenging. In addition, the conventional method
requires subjective analysis of CBF, e.g., manually counting by visual inspection. On the contrary, optical coherence
tomography (OCT) has been used to study the retina in ophthalmology as well as vasculature in cardiology, and offers
higher resolution than conventional computed tomography and magnetic resonance imaging. Based on this technology,
our lab specifically developed an ultra-high resolution OCT system to image the microstructure of the ciliated epithelial
cells. Doppler analysis was also performed to determine CBF. Lastly, we also developed a program that utilizes fast
Fourier transform to determine CBF under phase-contrast microscopy, providing a more objective method compared to
the current method.
In neonatal and pediatric patients who require long-term endotracheal intubation, the subglottic mucosa is most
susceptible to injury from the endotracheal tube. At present, there is no diagnostic modality to identify early signs of
subglottic mucosal pathology. Fourier-domain optical coherence tomography (FD-OCT) is a minimally-invasive
imaging modality which acquires high-resolution, 3D cross-sectional images of biological tissue. FD-OCT of the
neonatal and pediatric airways was conducted to evaluate subglottic microanatomy and histopathologic changes
associated with prolonged intubation.
FD-OCT of the larynx, subglottis and proximal trachea was conducted in pediatric and neonatal patients. OCT image
sets were analyzed by anatomic categorization (airway level), tissue segmentation and mucosa micrometry in MATLAB.
Subsequently, OCT data sets were rendered into digital 3D airway models in Mimics software. We report original
methods for subglottic OCT image processing and analysis.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.