Optical coherence tomography (OCT) is a rapid-developing biomedical imaging tool that can achieve micro-level resolution, high speed, non-destructive three-dimensional images. A variety of clinical applications in humans employs OCT, including ophthalmolo
Ophthalmic surgery involves manipulation of layered tissue structures on milli- to micrometer scales. Traditional surgical microscopes provide a two-dimensional view of the surgical field with limited depth perception which precludes accurate depth-resolved visualization of surgically-induced tissue morphology. Optical coherence tomography (OCT) enables non-contact exogenous contrast-free imaging of subsurface tissue microstructures, and is currently the gold standard for ophthalmic clinical diagnostics. Over the last decade, translation of OCT technologies to applications in surgical planning and guidance in ophthalmology has been an active area of research and commercialization. Clinical studies confirmed benefits of intraoperative OCT including verification that surgical goals have been ...
Optical coherence tomography (OCT) is a non-contact three-dimensional (3D) imaging modality which enables fast in vivo volumetric visualization of internal structures of biological tissues with high resolution. In this thesis, first, the application of OCT advanced extension - optical microangiography (OMAG) - was used to reveal the temporal profile of hemodynamic response to neural activation and the variation of depth-resolved blood flow changes in mouse cerebral cortex. The results showed that the largest hemodynamic response occurred in cortical layer IV. Second, OMAG and Doppler OMAG (DOMAG) techniques were applied to quantitatively evaluate the anesthesia effect on cerebral vessel morphology and blood flow ...
Mechanobiology is a prominent research field which seeks to elucidate the role of physical forces and mechanical interactions throughout various biological processes, including morphogenesis, wound healing, and cancer metastasis, among others. Traction force microscopy (TFM) is an important family of experimental techniques used by mechanobiologists to study and quantify the forces that cells exert upon their surroundings. Recent years have seen a growing demand for TFM methods capable of studying the dynamic, 3D, and collective behaviors of cells embedded within optically scattering media. However, traditional imaging modalities for TFM (e.g., confocal microscopy) do not currently allow researchers to satisfy ...
Optical coherence tomography (OCT) is a cross-sectional imaging modality based on low coherence light interferometry. OCT has been widely used in diagnostic ophthalmology and has found applications in other biomedical fields such as cancer detection and surgical guidance. In the Laboratory of Biophotonics Imaging and Sensing at New Jersey Institute of Technology, we developed a unique needle OCT imager based on a single fiber probe for breast cancer imaging. The needle OCT imager with sub-millimeter diameter can be inserted into tissue for minimally invasive in situ breast imaging. OCT imaging provides spatial resolution similar to histology and has the potential ...
Introduction The screening of diabetic retinopathy has been relied on fundus photography but since it is 2-dimensional, it is difficult to identify diabetic macular edema (DME), which is the most feared ocular complication related to diabetes. Optical coherence tomography (OCT) has been shown to be a useful tool in detecting and monitoring DME. The main objective of this study was to screen people with type 2 diabetes and find out how many patients have current diabetic macular edema and to compare different screening equipment by means of fundus photography and OCT when evaluating macular edema. Method The sample of this ...
The optic nerve head (ONH), located in the back of the eye, is a critical site in understanding the pathophysiology of glaucoma. However, longitudinal changes of the ONH as disease develops have not been well characterized. Our goal was to develop an improved tool to quantify these changes in an in vivo monkey model of glaucoma. Longitudinal spectral-domain optical coherence tomography (OCT) imaging of the ONH was performed every other week under manometric intraocular pressure (IOP) control (10 mmHg) in a monkey during baseline and after induction of unilateral experimental glaucoma. We developed a computational pipeline that applied digital volume ...
Nanocomposite materials play an increasingly important role in various application areas, be it in an industrial, medical or everyday environment. The unique properties of nanocomposites go beyond those of conventional composite materials. Because nanoparticles have a high surface-to-volume ratio such as carbon nanotubes, they can reinforce an embedding polymer host matrix mechanically, or they enhance the electrical material conductivity. A major challenge in the development of nanoparticles and nanocomposites is the control of particle size and shape, and of the uniform dispersion of nanoparticles in the host material. Conventional characterization techniques lack either resolution, or can only inspect details of ...
would like to thank my advisor Prof. Chao Zhou, who gave me the opportunity to pursue a higher-level education in the United States, and led me to the field of biomedical engineering. I still have the impression that I was attracted by the fast heartbeat of a Drosophila Prof. Zhou showed with a video in his presentation in Peking University in 2014. I was curious that how the fast heartbeat could be tracked using OCT. Fortunately, I got the opportunity to join the group during that summer. In the next several years during my PhD period, Prof. Zhou guided me ...
Optical coherence tomography (OCT) is a high speed, high resolution, noninvasive imaging technique that has seen applications across many clinical and biological research fields, with a particular focus in ophthalmic, cardiologic and dermatologic imaging. Ultrahigh speed OCT imaging has become of interest for high resolution, widefield in vivo imaging. Space division multiplexing optical coherence tomography (SDM-OCT) is a novel optical coherence tomography system which utilizes a parallel imaging approach to achieve ultrahigh imaging speeds. In this dissertation we develop an ophthalmic SDM-OCT system to obtain widefield structural and angiographic images of the human retina in vivo. With an 800 kHz ...
Ophthalmology is the only surgical specialty that routinely employs both microsurgical techniques and live intraoperative imaging, especially optical coherence tomography (OCT). Consequently, ophthalmic surgeons routinely face challenges in visualization and manipulation of small ocular tissues or in interpreting intraoperative imaging to guide their actions. This dissertation therefore seeks to advance the state-of-the-art in ophthalmic surgery with regards to manipulation, visualization, and interpretation. First, we address the interpretation challenge in ophthalmic surgery where live volumetric imaging from OCT systems recently incorporated into surgical microscopes has freed surgeons from the otherwise universal top-down viewpoint. These new viewpoints, however, disorient surgeons when directions ...
Optical coherence tomography (OCT) is a high-resolution, non-contact, three-dimensional imaging technique, which has revolutionized the diagnosis and treatment of retinal diseases. Visible-light OCT (vis-OCT) extends OCT by enabling retinal oximetry – the measurement of oxygen saturation of hemoglobin from within individual retinal blood vessels. Three advances in the vis-OCT technique are presented: an improved vis-OCT oximetry method based on circumpapillary scan and graph-search segmentation; the calibration, simulation, and correction of spectroscopic sensitivity rolloff for vis-OCT oximetry; and the measurement of the inner retinal oxygen metabolism in the 50/10 oxygen-induced retinopathy model, an animal model for human retinopathy of prematurity. Optical ...
The prostate is the gland located around the urethra beneath the bladder that produces most of the sperm fluid (figure 1). Prostate cancer (PCa) accounted for almost 1 in 5 new cancer diagnoses in males in the USA in 2017, and 1 in 8 men will develop invasive cancer in the prostate in their lifetime [1]. Prostate cancer is the second most common cancer in men (after skin cancer) and the second most common cause of cancer-related death (after lung cancer). Advances in screening, diagnosis, and treatment have led to an overall survival increase from 69% in 1991-1995 to 89 ...
The aim of this project was the implementation of optical coherence tomography (OCT), an invasive intracoronary imaging (ICI) tool used for the visualization of coronary arteries. The implementation was performed in a structured manner by: (1) A literature review into the current applications of OCT in relation to current standards; (2) A thesis feasibility study into clinical practices, professional views and other processes regarding ICI; (3) A Master’s thesis including a cost-effectiveness analysis (CEA) and the actual implementation of OCT at the department. The project started with a literature review about the current applications of OCT in relation to ...
The mechanism by which certain species of animals are able to detect the Earth’s magnetic field has remained a mystery for as long as we have known that they exhibit geomagnetic navigation. Certain species of bacteria are known to contain single chains of magnetite crystals, each with a diameter of ~50 nm, that are used to orient the bacteria. Searching for similar magnetoreceptors in larger animals requires a high-speed, high-resolution imaging system with the ability to detect single magnetic nanoparticles. Optical coherence tomography (OCT) is a biomedical imaging modality that produces 2D, cross-sectional images of optically turbid media with ...
Optical coherence tomography is a volumetric imaging technique that can differentiate brain regions with micron-scale resolution. Our group has previously developed an endoscopic full-field swept-source OCT system with the aim to provide real-time surgical guidance for the implantation of electrodes for deep brain stimulation. This thesis builds on our prior work. Due to the limitations in the resolution and contrast due to scattering from the tissue, to identify different types of neural tissues, we developed an image classification algorithm that use texture features and optical attenuation. The algorithm could classify three different brain regions in the ex vivo data set ...
In this thesis, we explored the opportunities of spatially resolved optical spectroscopy for neonatal healthcare. Hereto, we developed a setup that makes use of spectroscopic optical coherence tomography (sOCT). This technique allows for spectroscopic measurement of the attenuation of light within a confined measurement volume, without being influenced by surrounding tissues. Throughout this thesis, we explored the possibilities of sOCT for estimating tissue properties which are relevant to newborns. In this way, we hope to contribute to neonatal healthcare by enabling a non-invasive alternative for invasive blood sampling and by enabling more scientific research into human milk and lactation. The ...
Osteoarthritis (OA) is a debilitating degenerative joint disease affecting millions of patients worldwide and is characterized by loss of cartilage thickness and quality in affected joints. OA of the trapeziometacarpal (TMC) joint or thumb base joint especially gives rise to loss of hand function and disability. However, clinical imaging strategies have thus far been unable to accurately assess the thin cartilage layers lining small joints like the TMC joint. Moreover, a degree of discrepancy exists between clinical symptoms and OA features as seen on clinical imaging studies, hampering treatment choice. In an effort to eventually provide the clinician with additional ...
This dissertation reports the use of in utero optical coherence tomography to evaluate changes in vasculature in a developing murine fetal brain caused due to prenatal exposure to teratogens. Embryogenesis is a highly complex process that is extremely vulnerable to external factors. Proper visualization of embryonic development is crucial to understand the basic physiological processes and identify defects if any. This dissertation is divided into two major sections: 1) assessing teratogen induced changes in the murine fetal brain vasculature during the second trimester equivalent period (chapters 2-4) and 2) combining optical coherence tomography with Brillouin microscopy to image and evaluate ...
Optical coherence tomography (OCT) provides depth-resolved three-dimensional images allowing the visualization of subsurface microstructures over large areas in situ and thus is a promising tool for epithelial disease screening. However, it has generally been relegated to a nonspecific diagnostic tool because the optical reflectance (back-scattering) contrast in OCT images is poorly understood although some contrast agents are available for OCT. This thesis focuses on elucidating the microstructural and ultrastructural bases underlying optical contrast to explore if OCT could provide diagnostic information in epithelial tissues with specificity. We investigate the back-scattered intensity of different intracellular scatterers at the micrometer and nanometer ...
This thesis makes several important contributions to polarisation-sensitive optical coherence tomography (PS-OCT) through developing no el methods to effectively extract local contrast from birefringence and the orientation of the associated optic axis, at conventional and ultra-high resolution.
Optical Coherence Tomography (OCT) systems are making rapid progress into various areas ranging from medicine and health science up to non-medical areas such as quality control or biometrics. Various possible configurations are present in literature, but only a few exploit liquid crystals (LCs)-based device as a light source. The strength of OCT systems, compared with other three-dimensional imaging technologies, comes from a higher spatial resolution and a fast scanning rate that allows getting high-quality images of in vivo tissue samples. These qualities make OCT the perfect candidate for ophthalmology purpose, where the human eye moves quickly and randomly. The ...
Optical coherence tomography (OCT) is a noninvasive diagnostic imaging tool that has been established in various clinical fields. One of the most cited issue of OCT in clinical practices is the shortage of image depth range. This thesis proposes four novel techniques to significantly extend the depth range without compromising other imaging performances. The OCT depth range is fundamentally limited by two main factors, which are the axial field of view (FOV) and the system sensitivity. For standard OCT systems, the axial FOV can only be improved by decreasing the numerical aperture (NA) of the focusing optics, which unfortunately sacrifices ...
Biological functions rely on microvasculature to deliver oxygen and nutrients and carry away metabolic waste. Measuring microvascular oxygen saturation (sO2), the fraction of oxygensaturated hemoglobin relative to total hemoglobin (unsaturated + saturated) in the blood, can assess tissue oxygenation and provide insights into tissue metabolism, inflammation, and oxygen-related pathologies. Several major diseases, such as cancer, diabetes mellitus, cardiovascular diseases, hypertension, chronic kidney disease, and neurodegenerative diseases, are related to local microvascular sO2. Therefore, it is of crucial importance to demonstrate an accurate and reliable method to measure microvascular sO2 for early diagnosis, monitoring disease progression, and evaluating treatments of oxygen metabolism ...
