1. Featured Articles

    25-48 of 60 « 1 2 3 »
    1. Fiber-based polarization-sensitive OCT of the human retina with correction of system polarization distortions

      Fiber-based polarization-sensitive OCT of the human retina with correction of system polarization distortions

      In polarization-sensitive optical coherence tomography (PS-OCT) the use of single-mode fibers causes unpredictable polarization distortions which can result in increased noise levels and erroneous changes in calculated polarization parameters. In the current paper this problem is addressed by a new Jones matrix analysis method that measures and corrects system polarization distortions as a function of wavenumber by spectral analysis of the sample surface polarization state and deeper located birefringent tissue structures. This method was implemented on a passive-component depth-multiplexed swept-source PS-OCT system at 1040 nm which was theoretically modeled using Jones matrix calculus. High-resolution B-scan images are presented of the ...

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    2. Bioptigen Receives New US Patent for Intrasurgical OCT System

      Bioptigen Receives New US Patent for Intrasurgical OCT System

      Foundational patent for intrasurgical OCT marks the company's focus on emerging market for ophthalmic surgical imaging MORRISVILLE, NC August 5, 2014 Bioptigen Inc. announces today that it has received a new US Patent presenting innovative concepts integrating Optical Coherence Tomography (OCT) Systems to Surgical Microscopes. The patent, US 8,777,412 Surgical Microscopes Using Optical Coherence Tomography and Related Methods, by Buckland E.L., et. al. includes claims for independent OCT focus and zoom control for optimizing images from the cornea to the retina, and puts forward key elements of Bioptigen's approach for incorporating OCT into new and ...

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    3. Relationship between cholesterol crystals and culprit lesion characteristics in patients with stable coronary artery disease: an optical coherence tomography study

      Relationship between cholesterol crystals and culprit lesion characteristics in patients with stable coronary artery disease: an optical coherence tomography study

      Aims Some recent studies have reported the role of cholesterol crystals (ChCs) in plaque rupture in patients with coronary artery disease. We used optical coherence tomography (OCT) to investigate the characteristics of coronary plaques that were associated with derived ChCs. Methods We evaluated 101 subjects with stable coronary artery disease who underwent OCT. We compared the OCT findings of the culprit lesions with ChCs to those without ChCs and investigated the background characteristics. Results ChCs were observed in culprit lesions of 39 patients. The frequencies of spotty calcification, microchannel structure, and lipid-rich plaque were significantly higher in patients with ChCs ...

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    4. A high-efficiency fiber-based imaging system for co-registered autofluorescence and optical coherence tomography

      A high-efficiency fiber-based imaging system for co-registered autofluorescence and optical coherence tomography

      We present a power-efficient fiber-based imaging system capable of co-registered autofluorescence imaging and optical coherence tomography (AF/OCT). The system employs a custom fiber optic rotary joint (FORJ) with an embedded dichroic mirror to efficiently combine the OCT and AF pathways. This three-port wavelength multiplexing FORJ setup has a throughput of more than 83% for collected AF emission, significantly more efficient compared to previously reported fiber-based methods. A custom 900 µm diameter catheter ‒ consisting of a rotating lens assembly, double-clad fiber (DCF), and torque cable in a stationary plastic tube ‒ was fabricated to allow AF/OCT imaging of small airways ...

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    5. Morphologic Characteristics of Eroded Coronary Plaques: A Combined Angiographic, Optical Coherence Tomography, and Intravascular Ultrasound Study

      Morphologic Characteristics of Eroded Coronary Plaques: A Combined Angiographic, Optical Coherence Tomography, and Intravascular Ultrasound Study

      Plaque erosion accounts for about one-third of acute coronary syndrome (ACS) [1]. Systemic milieu such as high inflammatory and/or thrombogenic status may be an essential precondition for the occurrence of plaque erosion [2]. However, ACS patients frequently have multiple lesions and not all plaques develop erosion resulting in occlusive thrombus formation. Since the systemic milieu is the same, we hypothesized that plaque morphological features would be different between eroded culprit plaques (ECP) and non-eroded, non-culprit plaques (NENCP).

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    6. Stability in computed optical interferometric tomography (Part II): in vivo stability assessment

      Stability in computed optical interferometric tomography (Part II): in vivo stability assessment

      Stability is of utmost importance to a wide range of phase-sensitive processing techniques. In Doppler optical coherence tomography and optical coherence elastography, in addition to defocus and aberration correction techniques such as interferometric synthetic aperture microscopy and computational/digital adaptive optics, a precise understanding of the system and sample stability helps to guide the system design and choice of imaging parameters. This article focuses on methods to accurately and quantitatively measure the stability of an imaging configuration in vivo . These methods are capable of partially decoupling axial from transverse motion and are compared against the stability requirements for computed optical ...

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    7. Longitudinal vascular dynamics following cranial window and electrode implantation measured with speckle variance optical coherence angiography

      Longitudinal vascular dynamics following  cranial window and electrode implantation  measured with speckle variance optical  coherence angiography

      Speckle variance optical coherence angiography (OCA) was used to characterize the vascular tissue response from craniotomy, window implantation, and electrode insertion in mouse motor cortex. We observed initial vasodilation ~40% greater than original diameter 2-3 days post-surgery (dps). After 4 weeks, dilation subsided in large vessels (>50 µm diameter) but persisted in smaller vessels (25-50 µm diameter). Neovascularization began 8-12 dps and vessel migration continued throughout the study. Vasodilation and neovascularization were primarily associated with craniotomy and window implantation rather than electrode insertion. Initial evidence of capillary re-mapping in the region surrounding the implanted electrode was manifest in OCA image ...

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    8. Two-year vessel healing after everolimus-eluting stent implantation: Serial assessment by optical coherence tomography

      Two-year vessel healing after everolimus-eluting stent implantation: Serial assessment by optical coherence tomography

      Background Previous reports have suggested the importance of delayed arterial healing and the development of neoatherosclerosis as major contributors to stent thrombosis and delayed restenosis. The difference of in vivo assessment of long-term vessel healing between first-generation drug-eluting stents and current generation everolimus-eluting stents (EESs) is limited. The aim of this study was to evaluate long-term arterial healing in EES in comparison with the first generation sirolimus-eluting stents (SES). Methods We evaluated 31 EES (23 patients) and 8 SES (7 patients) by serial optical coherence tomography at 12 months (mid-phase) and 24 months (late-phase) after stenting and evaluated the change ...

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    9. Optical coherence tomography today: speed, contrast, and multimodality

      Optical coherence tomography today: speed, contrast, and multimodality

      In the last 25 years, optical coherence tomography (OCT) has advanced to be one of the most innovative and most successful translational optical imaging techniques, achieving substantial economic impact as well as clinical acceptance. This is largely owing to the resolution improvements by a factor of 10 to the submicron regime and to the imaging speed increase by more than half a million times to more than 5 million A-scans per second, with the latter one accomplished by the state-of-the-art swept source laser technologies that are reviewed in this article. In addition, parallelization of OCT detection, such as line-field and ...

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    10. Automated assessment of the remineralization of artificial enamel lesions with polarization-sensitive optical coherence tomography

      Automated assessment of the remineralization of artificial enamel lesions with polarization-sensitive optical coherence tomography

      Accurate measurement of the highly mineralized transparent surface layer that forms on caries lesions is important for diagnosis of the lesion activity because chemical intervention can slow or reverse the caries process via remineralization. Previous in-vitro and in-vivo studies have demonstrated that polarization-sensitive optical coherence tomography (PS-OCT) can nondestructively image the subsurface lesion structure and the highly mineralized transparent surface zone of caries lesions. The purpose of this study was to develop an approach to automatically process 3-dimensional PS-OCT images and to accurately assess the remineralization process in simulated enamel lesions. Artificial enamel lesions were prepared on twenty bovine enamel ...

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    11. Dermascope guided multiple reference optical coherence tomography

      Dermascope guided multiple reference optical coherence tomography

      In this paper, we report the feasibility of integrating a novel low cost optical coherence tomography (OCT) system with a dermascope for point-of-care applications. The proposed OCT system is based on an enhanced time-domain optical coherence tomographic system, called multiple reference OCT (MR-OCT), which uses a single miniature voice coil actuator and a partial mirror for extending the axial scan range. The system can simultaneously register both the superficial dermascope image and the depth-resolved OCT sub-surface information by an interactive beam steering method. A practitioner is able to obtain the depth resolved information of the point of interest by simply ...

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    12. Terahertz imaging based on optical coherence tomography

      Terahertz imaging based on optical coherence tomography

      Three-dimensional (3D) terahertz (THz) imaging or THz tomography has recently proven to be useful for nondestructive testing of industrial materials and structures. In place of previous imaging techniques such as THz pulsed/continuous-wave radar and THz computed tomography, we propose a THz optical coherence tomography using photonics- and electronics-based THz sources, and demonstrate thickness measurement and tomographic imaging in frequency regions from 400 to 800 GHz.

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      Mentions: Osaka University
    13. Fully Integrated High-Speed Intravascular OCT/NIRF Structural/Molecular Imaging In Vivo Using a Clinically Available Near-Infrared Fluorescence–Emitting Indocyanine Green to Detect Inflamed Lipid-Rich Atheromata in Coronary-Sized Vessels

      Fully Integrated High-Speed Intravascular OCT/NIRF Structural/Molecular Imaging In Vivo Using a Clinically Available Near-Infrared Fluorescence–Emitting Indocyanine Green to Detect Inflamed Lipid-Rich Atheromata in Coronary-Sized Vessels

      Background— Lipid-rich inflamed coronary plaques a reprone to rupture. The purpose of this study was to assess lipid-rich inflamed plaques invivo using fully integrated high-speed optical coherence tomography (OCT)/ near-infrared fluorescence (NIRF) molecular imaging with a Food and Drug Administration– a pproved indocyanine green (ICG). Methods a nd Results— A n integrated high-speed intravascular OCT/NIRF imaging c a theter a nd a du a l-mod a l OCT/NIRF system were constructed b a sed on a cl in ic a l OCT pl a tform. For imaging lipid-rich inflamed plaques, the Food and Drug Administration– approved NIRF-emitting ICG ...

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    14. Stability in computed optical interferometric tomography (Part I): Stability requirements

      Stability in computed optical interferometric tomography (Part I): Stability requirements

      As imaging systems become more advanced and acquire data at faster rates, increasingly dynamic samples can be imaged without concern of motion artifacts. For optical interferometric techniques such as optical coherence tomography, it often follows that initially, only amplitude-based data are utilized due to unstable or unreliable phase measurements. As systems progress, stable phase maps can also be acquired, enabling more advanced, phase-dependent post-processing techniques. Here we report an investigation of the stability requirements for a class of phase-dependent post-processing techniques – numerical defocus and aberration correction with further extensions to techniques such as Doppler, phase-variance, and optical coherence elastography. Mathematical ...

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    15. Single input state polarization sensitive swept source optical coherence tomography based on an all single mode fiber interferometer

      Single input state polarization sensitive swept source optical coherence tomography based on an all single mode fiber interferometer

      We present a newly developed single mode fiber based swept source polarization sensitive optical coherence tomography system using a single input state at 1040 nm. Two non-polarizing fiber based beam splitters are combined to form a Mach-Zehnder interferometer, while two polarizing beam splitters are used to obtain a polarization sensitive detection. Both types of beam splitters solely feature conventional single mode fibers. Polarization control paddles are used to set and maintain the polarization states in the fibers of the interferometer and detection unit. By use of a special paddle alignment scheme we are able to eliminate any bulk optic wave ...

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    16. The Prospective Intraoperative and Perioperative Ophthalmic ImagiNg with Optical CoherEncE TomogRaphy (PIONEER) Study: 2-year Results

      The Prospective Intraoperative and Perioperative Ophthalmic ImagiNg with Optical CoherEncE TomogRaphy (PIONEER) Study: 2-year Results

      Purpose To evaluate the feasibility, safety, and utility of intraoperative optical coherence tomography (OCT) for use during ophthalmic surgery. Design Prospective, consecutive, case series Methods A prospective, single-center, consecutive, case series was initiated to assess intraoperative OCT in ophthalmic surgery. Intraoperative scanning was performed with a microscope mounted spectral domain OCT system. Disease specific or procedure-specific imaging protocols (e.g., scan type, pattern, size, orientation, density) were utilized for anterior and posterior segment applications. A surgeon feedback form was recorded as part of the study protocol to answer specific questions regarding intraoperative OCT utility immediately after the surgical procedure was ...

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    17. Intracoronary Optical Coherence Tomography: Insights from Clinical Research—What Do We Need to Learn?

      Intracoronary Optical Coherence Tomography: Insights from Clinical Research—What Do We Need to Learn?

      Optical coherence tomography (OCT) is a high-resolution technology for imaging of biological tissues that has shown tremendous potential for intracoronary use. Based on near-infrared light rather than ultrasound, catheter-based OCT provides cross-sectional images of the vessel wall and related devices in a histology-like manner. At present, OCT is primarily being used in research to better characterize and understand the pathophysiology of vulnerable plaques and to study the acute and long-term effects of coronary stent implantation. The present review provides the interventional cardiologist with a summary of the clinical research involving OCT, with an emphasis on specific challenges and how these ...

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      Mentions: Maria D. Radu
    18. Optical coherence tomography applied to tests of skin care products in humans – a case study

      Optical coherence tomography applied to tests of skin care products in humans – a case study

      Background/purpose When evaluating skin care products for human skin, quantitative test methods need to be simple, precise and reliable. Optical coherence tomography (OCT), provides high-resolution sectional images of translucent materials to a depth of a few millimeters, a technique usually applied to medical measurements in ophthalmology and dermatology. This study aimed to demonstrate the application of OCT as the main technique for monitoring changes in skin topography during tests of a wrinkle-reduction product in humans. Methods We used a commercial OCT apparatus to perform clinical examinations of skin roughness in treated and non-treated sites in the periorbital region of ...

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      Mentions: Marcus P. Raele
    19. ABSORB Biodegradable Stents Versus Second-Generation Metal Stents : A Comparison Study of 100 Complex Lesions Treated Under OCT Guidance

      ABSORB Biodegradable Stents Versus Second-Generation Metal Stents : A Comparison Study of 100 Complex Lesions Treated Under OCT Guidance

      Objectives The aim of this study was to compare the acute performance of the PLLA ABSORB bioresorbable vascular scaffold (BVS) (Abbott Vascular, Santa Clara, California) with second-generation metal drug-eluting stents (DES) in complex coronary artery lesions. Background Thick polymer-based BVS have different mechanical properties than thin second-generation DES. Data on the acute performance of BVS are limited to simple coronary lesions treated in trials with strict inclusion criteria. Methods Fifty complex coronary lesions (all type American College of Cardiology/American Heart Association B2-C) treated with a BVS undergoing a final optical coherence tomography (OCT) examination were compared with an equal ...

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    20. Postdoctoral Research Associate Opening at University of Liverpool

      Postdoctoral Research Associate Opening at University of Liverpool

      Postdoctoral Research Associate £31,644 - £36,661 pa Faculty of Science and Engineering, Institute of Electrical Engineering and Electronics, Department of Electrical Engineering and Electronics Location: University Campus Ref: R-585803/WWW Closing date for receipt of applications: Fri, 22 Aug 2014 17:00:00 BST To undertake a project “ I ntelligent Manufacturing of Pharmaceutical Film Coating Using Terahertz Pulsed Imaging, Optical Coherence Tomography and Numerical Modelling ” in collaboration with Cambridge University. You will primarily focus on the development and integration of an optical coherence tomography (OCT) sensor for online monitoring and quality control of pharmaceutical coating process. The duties include ...

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    21. Viewing Dentistry in a New Light

      Viewing Dentistry in a New Light

      Dental X-rays expose patients to radiation, require time to process, and can only “see” a limited amount inside the mouth. Now new optical techniques developed by UC San Francisco’s Daniel Fried , PhD, use light to take instantaneous digital images that can provide a better picture of our teeth and could one day zap cavities with pinpoint precision. Daniel Fried, PhD, speaks with Leon Chung, a dental research fellow in his lab. Photo by Susan Merrell Fried, a professor in the School of Dentistry’s Division of Biomaterials and Bioengineering in the Department of Preventive and Restorative Dental Sciences, is ...

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    22. Versatile Swept Source With Adjustable Coherence Length

      Versatile Swept Source With Adjustable Coherence Length

      An electronically controlled optical swept source at 1550 nm using mode locking in a dispersive ring cavity is described. Active mode-locking was achieved by directly modulating the current of a semiconductor optical amplifier (SOA) used as a gain medium. In the static regime, parameters such as linewidth, tuning bandwidth, and contrast were measured, whereas the axial range was determined dynamically. Two types of fiber, dispersion compensation and single mode, are employed in the laser ring cavity. It is demonstrated that the relative lengths of the two types of fiber have little effect on the linewidth, whereas more control on the ...

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    23. Real-time three-dimensional imaging of epidermal splitting and removal by high-definition optical coherence tomography

      Real-time three-dimensional imaging of epidermal splitting and removal by high-definition optical coherence tomography

      Background While real-time 3-D evaluation of human skin constructs is needed, only 2-D non-invasive imaging techniques are available. Objective Evaluation of the potential of High-Definition Optical Coherence Tomography (HD-OCT) for real-time 3-D assessment of the epidermal splitting and de-cellularisation. Methods Human skin samples were incubated with four different agents: Dispase II, NaCl 1M, Sodium Dodecyl Sulfate (SDS) and Triton X-100. Epidermal splitting, dermo-epidermal junction, acellularity and 3-D architecture of dermal matrices were evaluated by High-Definition Optical Coherence Tomography before and after incubation. Real-time 3-D HD-OCT assessment was compared with 2-D en face assessment by Reflectance Confocal Microscopy (RCM). (Immuno)histopathology ...

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    24. Feasibility of the Assessment of Cholesterol Crystals in Human Macrophages Using Micro Optical Coherence Tomography

      Feasibility of the Assessment of Cholesterol Crystals in Human Macrophages Using Micro Optical Coherence Tomography

      The presence of cholesterol crystals is a hallmark of atherosclerosis, but until recently, such crystals have been considered to be passive components of necrotic plaque cores. Recent studies have demonstrated that phagocytosis of cholesterol crystals by macrophages may actively precipitate plaque progression via an inflammatory pathway, emphasizing the need for methods to study the interaction between macrophages and crystalline cholesterol. In this study, we demonstrate the feasibility of detecting cholesterol in macrophages in situ using Micro-Optical Coherence Tomography (µOCT), an imaging modality we have recently developed with 1-µm resolution. Macrophages containing cholesterol crystals frequently demonstrated highly scattering constituents in ...

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