Longitudinal imaging of a 3D model of calcific aortic valve disease, which consisted of co-cultured GFP+ Valve Endothelial Cells (VEC) and Valve Interstitial Cells (VIC), was performed with a combined Optical Coherence Microscopy (OCM), confocal reflectance and fluorescence microscopy system. The acquired confocal volumes depicted the VEC morphological changes and migration as well as collagen fiber alignment. With the aid of computational refocusing and multi-volume processing, the OCM datasets could visualize VIC cell bodies, matrix remodeling, nodule formation and calcific deposits. The complementary information derived using this combined approach could help unravel the cellular mechanisms leading to aortic valve calcification.
A combined 1300 nm Optical Coherence Microscopy (OCM) and 488 nm confocal reflectance/ fluorescence microscopy system was designed to perform high-resolution, high-specificity imaging of collagen-embedded spheroids. Spheroids of Hyaluronic Acid (HA) synthase-overexpressing breast epithelial cells alone, or co-cultured with adipose stromal cells were imaged. The volumes, acquired either after fixing and staining or longitudinally with labeling, enabled the visualization of the spheroid morphology, luminal structures, cellular organization, and collagen matrix remodeling. The morphology and internal lumen structures of spheroids, as large as 500 μm in diameter, could be obtained from the OCM volumes, even in the presence of dense collagen matrix surrounding the spheroids. The confocal stacks provided superior specificity to discriminate cells from the compacted collagen along the spheroid’s periphery, up to a depth of ~120 μm. The combined use of OCM and confocal imaging on these spheroid models has added to our understanding of how HA may contribute to tumor initiation and invasion.
A fiber-optic probe with a low numerical aperture lens at its tip is better suited for imaging the large airways, as the distance between the probe and the tissue surface is unknown and variable. A multi-segment, all-fiber lens, that consists of a section of coreless fiber (CF) and graded index fiber, followed by a CF ball lens section is described. With this design, lenses with a working distance (WD) greater than 7 mm can be obtained with ball diameters as small as 365 µm and nearly collimated beams with WD greater than 14 mm are demonstrated with a ~500 µm ball tip.
Methods to quantify airway wall compliance are needed for diagnostics, stratification, and monitoring in upper airway disorders and inhalation injury. Endoscopic OCT tracks micron-scale airway deformation during respiration, and in conjunction with in situ pressure monitoring, maps local and cross-sectional compliances. Airway phantoms are employed to validate the accuracy of the methods, and experiments in ex vivo and in vivo pig airways are compared to CINE CT. Findings include the importance of centroid tracking, best practices for endoscopic procedures, hysteresis in airway pressure-volume curves, changes in elastic properties during burn injury, and modeling methods to extract elasticity and viscoelasticity.
Objective measurement of the nasal valve region is valuable for the assessment of functional rhinoplasty surgical outcomes. Anatomical optical coherence tomography (aOCT) is an imaging modality that may be used to obtain real-time, quantitative, and volumetric scans of the nasal airway. We aim to evaluate if volumetric aOCT imaging is useful for the examination of the nasal valve region before and after functional rhinoplasty procedures. aOCT scans of the nasal valves were performed on four cadaveric heads before and after spreader graft and butterfly graft procedures. The resulting aOCT images were compared against video endoscopy images, and the segmented volumes of the nasal airway obtained from aOCT scans were compared with computed tomography (CT) derived volumes acquired under the same conditions. The aOCT-derived volumes match the CT volumes closely, with a mean Dice similarity coefficient of 0.88 and a mean Hausdorff distance of 2.3 mm. Furthermore, the aOCT images were found to represent the shape of the nasal cavity accurately. Due to its ability to perform real-time, quantitative, and accurate evaluation of the nasal airway, aOCT imaging is a promising modality for the objective assessment of the nasal valves before and after functional rhinoplasty procedures.
KEYWORDS: Optical coherence tomography, Computed tomography, In vivo imaging, Data acquisition, Endoscopy, Imaging systems, Physical sciences, Range imaging, Video, Tissues
It is hypothesized that the local, viscoelastic (time-dependent) properties of the airway are important to accurately model and ultimately predict dynamic airway collapse in airway obstruction. Toward this end, we present a portable, endoscopic, swept-source anatomical optical coherence tomography (aOCT) system combined with a pressure catheter to capture local airway dynamics in vivo during respiration. aOCT scans were performed in the airways of a mechanically ventilated pig under paralysis with dynamic and static ventilation protocols. Validation of dynamic aOCT luminal cross-sectional area (CSA) measurements against Cine CT, obtained during the same exam, showed an aggregate difference of 15 % ± 3 % . aOCT-derived CSA obtained in the in vivo trachea also exhibited hysteresis as a function of pressure, depicting the viscoelastic nature of the airway wall. The volumetric imaging capabilities were validated by comparing aOCT- and CT-derived geometries of the porcine airway spanning nine generations from the trachea to the bronchioles. The ability to delineate regional differences in airway viscoelastic properties, by measuring airway deformation using aOCT combined with intraluminal pressure, paves the way to patient-specific models of dynamic airway collapse.
To aid in diagnosis and treatment of upper airway obstructive disorders (UAOD), we propose anatomic Optical Coherence Tomography (aOCT) for endoscopic imaging of the upper airway lumen with high speed and resolution. aOCT and CT scans are performed sequentially on in vivo swine to compare dynamic airway imaging data. The aOCT system is capable of capturing the dynamic deformation of the airway during respiration. This may lead to methods for airway elastography and aid in our understanding of dynamic collapse in UAOD.
We describe a novel, multi-modal imaging protocol for validating quantitative dynamic airway imaging performed using anatomical Optical Coherence Tomography (aOCT). The aOCT system consists of a catheter-based aOCT probe that is deployed via a bronchoscope, while a programmable ventilator is used to control airway pressure. This setup is employed on the bed of a Siemens Biograph CT system capable of performing respiratory-gated acquisitions. In this arrangement the position of the aOCT catheter may be visualized with CT to aid in co-registration. Utilizing this setup we investigate multiple respiratory pressure parameters with aOCT, and respiratory-gated CT, on both ex vivo porcine trachea and live, anesthetized pigs. This acquisition protocol has enabled real-time measurement of airway deformation with simultaneous measurement of pressure under physiologically relevant static and dynamic conditions- inspiratory peak or peak positive airway pressures of 10-40 cm H2O, and 20-30 breaths per minute for dynamic studies. We subsequently compare the airway cross sectional areas (CSA) obtained from aOCT and CT, including the change in CSA at different stages of the breathing cycle for dynamic studies, and the CSA at different peak positive airway pressures for static studies. This approach has allowed us to improve our acquisition methodology and to validate aOCT measurements of the dynamic airway for the first time. We believe that this protocol will prove invaluable for aOCT system development and greatly facilitate translation of OCT systems for airway imaging into the clinical setting.
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