1. 1-24 of 292 1 2 3 4 ... 11 12 13 »
    1. Imaging cellular structures of atherosclerotic coronary arteries using circumferentially scanning micro-optical coherence tomography fiber probe ex vivo

      Imaging cellular structures of atherosclerotic coronary arteries using circumferentially scanning micro-optical coherence tomography fiber probe ex vivo

      Development and progression of coronary atherosclerotic lesions is mediated by a number of cellular components, which are not readily visualized using the current clinical investigation tools. Visualizing these cellular components in situ and in vivo may allow early detection of the vulnerable plaques, with implications for coronary artery disease (CAD) therapy and for the prevention of acute myocardial infarction (AMI). In this study, we have developed a fiber-optic micro-optical coherence tomography (µOCT) probe for intravascular use. We conducted ex vivo imaging experiments in normal swine aorta and human atherosclerotic coronary arteries, and demonstrate that the fiber-probe based µOCT could delineate ...

      Read Full Article
    2. Geometric Validation of Continuous, Finely-Sampled 3D Reconstructions from aOCT and CT in Upper Airway Models

      Geometric Validation of Continuous, Finely-Sampled 3D Reconstructions from aOCT and CT in Upper Airway Models

      Identification and treatment of obstructive airway disorders (OADs) is greatly aided by imaging of the geometry of the airway lumen. Anatomical optical coherence tomography (aOCT) is a promising high-speed and minimally-invasive endoscopic imaging modality for providing micrometer-resolution scans of the upper airway. Resistance to airflow in OADs is directly caused by reduction in luminal cross-sectional area (CSA). It is hypothesized that aOCT can produce airway CSA measurements as accurate as that from computed tomography (CT). Scans of machine hollowed cylindrical tubes were used to develop methods for segmentation and measurement of airway lumen in CT and aOCT. Simulated scans of ...

      Read Full Article
    3. Quantitative evaluation of skin surface roughness using optical coherence tomography in vivo

      Quantitative evaluation of skin surface roughness using optical coherence tomography in vivo

      The quantitative monitoring of skin topography is important in the field of cosmetics and dermatology. The most widespread method for determining skin roughness in vivo is to use skin microrelief, PRIMOS device, which allows a noninvasive, fast and direct measurement of the skin surface. However, it has drawbacks, such as the interference of backscattering from volumetric skin and motion artifacts. In this study, we demonstrate the potential of OCT for providing reliable and quantitative skin surface roughness. In order to evaluate the performance of OCT for skin surface analysis, different types of skin phantoms were fabricated and measured. We utilized ...

      Read Full Article
    4. A miniature endoscopic optical coherence tomography probe based on C-lens

      A miniature endoscopic optical coherence tomography probe based on C-lens

      We present a novel miniature endoscopic OCT probe based on an electrothermal microelectromechanical (MEMS) mirror and a C-lens. The MEMS mirror has a relatively large mirror plate of 0.5 mm×0.5 mm on a small chip size of 1.5 mm×1.3 mm, leading to the outer diameter of the endoscopic probe down to only 2.5 mm so that the probe is capable of being inserted through the biopsy channel of a conventional endoscope. A long focal length of 12 mm is achieved by properly designing the C-lens. Compared to commonly used GRIN lenses, C-lenses have ...

      Read Full Article
    5. A Fully Automated 3D In-vivo Delineation and Shape Parameterization of the Human Lamina Cribrosa in Optical Coherence Tomography

      A Fully Automated 3D In-vivo Delineation and Shape Parameterization of the Human Lamina Cribrosa in Optical Coherence Tomography

      Objective: A fully automated method for delineation of the lamina cribrosa in optical coherence tomography (OCT) is proposed. It assesses the 3D shape of the lamina cribrosa in-vivo, based on a series of OCT B-scans. Methods: The algorithm has several image processing steps and it is based on active contour detection performed along three orthogonal directions of the B-scan data cuboid. Further, the delineated 3D lamina cribrosa shape is parameterized with a fourth-order polynomial of two variables, P[x, y] using the least-squares method. Data sets from a total of 255 subjects from three groups were analyzed: 92 primary open ...

      Read Full Article
    6. Decreasing the Size of a Spectral Domain Optical Coherence Tomography System with Cascaded Arrayed Waveguide Gratings in a Photonic Integrated Circuit

      Decreasing the Size of a Spectral Domain Optical Coherence Tomography System with Cascaded Arrayed Waveguide Gratings in a Photonic Integrated Circuit

      This paper describes a proof-of-concept of a miniaturized spectral-domain optical coherence tomography system, based on photonic integrated circuit (PIC) technology. The integrated optics 512-channel spectrometer consists of cascaded arrayed waveguide gratings (AWG) with the output waveguides directly attached to a CCD detector. The spectrometer has a center wavelength of 850 nm and a spectral sampling interval of 0.22 nm. The PIC has a footprint of 2.0x2.7 cm2. The wavelength response of the cascaded AWG spectrometer is calibrated with a tunable laser. Free space OCT measurements are done with a mirror as sample. The signal-to-noise ratio is ~77 ...

      Read Full Article
    7. Optical Coherence Tomography as an Oral Cancer Screening Adjunct in a Low Resource Settings

      Optical Coherence Tomography as an Oral Cancer Screening Adjunct in a Low Resource Settings

      Oral cancer is the sixth most common cancer worldwide, predominantly seen in low and middle-income countries (LMIC). Two thirds of all cases are detected at a late stage when prognosis and treatment outcomes are poor. Oral lesions are commonly detected by visual inspection, followed by invasive surgical biopsy and time consuming histopathological analysis. Optical Coherence Tomography (OCT), a minimally invasive tomographic imaging technology, can be used to non-invasively identify premalignant or malignant change in the oral mucosa. In this study, a mobile OCT imaging system was designed, constructed and tested for its performance as a point-of-care oral diagnostic device. Twenty ...

      Read Full Article
    8. Establishment of an Automated Algorithm Utilizing Optical Coherence Tomography and Micro-Computed Tomography Imaging to Reconstruct the 3D Deformed Stent Geometry

      Establishment of an Automated Algorithm Utilizing Optical Coherence Tomography and Micro-Computed Tomography Imaging to Reconstruct the 3D Deformed Stent Geometry

      Percutaneous coronary intervention (PCI) is the prevalent treatment for coronary artery disease, with hundreds of thousands of stents implanted annually. Computational studies have demonstrated the role of biomechanics in the failure of vascular stents, but clinical studies is this area are limited by a lack of understanding of the deployed stent geometry, which is required to accurately model and predict the stent induced in vivo biomechanical environment. Herein, we present an automated method to reconstruct the 3D deployed stent configuration through the fusion of optical coherence tomography (OCT) and micro-computed tomography (μCT) imaging data. In an experimental setup, OCT and ...

      Read Full Article
    9. Three Dimensional Full-Range Dual-Band Fourier Domain Optical Coherence Tomography Accelerated by Graphic Processing Unit

      Three Dimensional Full-Range Dual-Band Fourier Domain Optical Coherence Tomography Accelerated by Graphic Processing Unit

      The authors present a graphic processing unit (GPU) accelerated three-dimensional (3D) full-range dual-band Fourier domain optical coherence tomography (FD-OCT) using a LabVIEW GPU program with GPU-adaptable algorithms. GPU can dramatically reduce the image processing time, but programing on GPU is more complex than that on central processing unit (CPU). This work implements GPU computing interfaced with LabVIEW, using a LabVIEW GPU analysis toolkit, which significantly reduces the programing complexity. The selected algorithms are suitable for GPU computing in multi-band FD-OCT. The developed system overcomes the problem of long image processing time relative to data acquisition time in CPU. A 65 ...

      Read Full Article
    10. Monitoring Acute Stroke in Mouse Model Using Laser Speckle Imaging-Guided Visible-Light Optical Coherence Tomography

      Monitoring Acute Stroke in Mouse Model Using Laser Speckle Imaging-Guided Visible-Light Optical Coherence Tomography

      Objective: Monitoring hemodynamic and vascular changes in the acute stages of mouse stroke models is invaluable in studying ischemic stroke pathophysiology. However, there lacks a tool to simultaneously and dynamically investigate these changes. Methods: We integrated laser speckle imaging (LSI) and visible-light optical coherence tomography (Vis-OCT) to reveal dynamic vascular responses in acute stages in the distal middle cerebral artery occlusion (dMCAO) model in rodents. LSI provides full-field, real-time imaging to guide Vis-OCT imaging and monitor the dynamic cerebral blood flow (CBF). Vis-OCT offers depth-resolved angiography and oxygen saturation (sO 2 ) measurements. Results: Our results showed detailed CBF and vasculature ...

      Read Full Article
    11. Mapping and Quantitating Penetrating Vessels in Cortical Brain Using Eigen-Decomposition of OCT Signals and Subsequent Principal Component Analysis

      Mapping and Quantitating Penetrating Vessels in Cortical Brain Using Eigen-Decomposition of OCT Signals and Subsequent Principal Component Analysis

      Penetrating vessels bridge the mesh of communicating vessels on the surface of the cortex with the subsurface microvascular beds that feed the underlying neural tissue. Their accurate identification in vivo is important in the investigations of neural degenerative diseases, e.g., Alzheimer's disease and stroke. Here, we propose an efficient method to automatically map cortical penetrating vessels based on an eigen decompensation analysis of the optical coherence tomography (OCT) and OCT angiographic signals. We first project the ensemble of repeated OCT signals into a feature space that represents the power spectral components of eigenvectors through a well-known eigen-decomposition method ...

      Read Full Article
    12. Automatically Determining the Confocal Parameters from OCT B-Scans for Quantification of the Attenuation Coefficients

      Automatically Determining the Confocal Parameters from OCT B-Scans for Quantification of the Attenuation Coefficients

      The attenuation coefficient is a relevant biomarker for many diagnostic medical applications. Recently, the Depth- Resolved Confocal (DRC) technique was developed to automatically estimate the attenuation coefficients from Optical Coherence Tomography (OCT) data with pixel-level resolution. However, DRC requires that the confocal function parameters (i.e., focal plane location and apparent Rayleigh range) be known a priori. In this paper we present the autoConfocal algorithm: a simple, automatic method for estimating those parameters directly from OCT imagery when the focal plane is within the sample. We present autoConfocal+DRC results on phantom data, ex-vivo biological tissue data, and in-vivo clinical ...

      Read Full Article
    13. Extracting Blood Vessels From Full-Field OCT Data of Human Skin by Short-Time RPCA

      Extracting Blood Vessels From Full-Field OCT Data of Human Skin by Short-Time RPCA

      Recent advances in optical coherence tomography (OCT) lead to the development of OCT angiography to provide additional helpful information for diagnosis of diseases like basal cell carcinoma. In this paper, we investigate how to extract blood vessels of human skin from full-field OCT (FF-OCT) data using the robust principal component analysis (RPCA) technique. Specifically, we propose a short-time RPCA method that divides the FF-OCT data into segments and decomposes each segment into a low-rank structure representing the relatively static tissues of human skin and a sparse matrix representing the blood vessels. The method mitigates the problem associated with the slow-varying ...

      Read Full Article
    14. Wavelength Dependence of Ultrahigh-Resolution Optical Coherence Tomography Using Supercontinuum for Biomedical Imaging

      Wavelength Dependence of Ultrahigh-Resolution Optical Coherence Tomography Using Supercontinuum for Biomedical Imaging

      Optical coherence tomography (OCT) is a noninvasive cross-sectional imaging technique with micrometer resolution. The theoretical axial resolution is determined by the center wavelength and bandwidth of the light source, and the wider the bandwidth, the higher the axial resolution. The characteristics of OCT imaging depend on the optical wavelength used. In this paper, we investigated the wavelength dependence of ultrahigh-resolution (UHR) OCT using a supercontinuum for biomedical imaging. Wideband, high-power, low-noise supercontinua (SC) were generated at λ = 0.8, 1.1, 1.3, and 1.7 μ m based on ultrashort pulses and nonlinear fibers. The wavelength dependence of OCT imaging was ...

      Read Full Article
    15. Towards Robotic Eye Surgery: Marker-free, Online Hand-eye Calibration using Optical Coherence Tomography Images

      Towards Robotic Eye Surgery: Marker-free, Online Hand-eye Calibration using Optical Coherence Tomography Images

      Ophthalmic microsurgery is known to be a challenging operation, which requires very precise and dexterous manipulation. Image guided robot-assisted surgery (RAS) is a promising solution that brings significant improvements in outcomes and reduces the physical limitations of human surgeons. However, this technology must be further developed before it can be routinely used in clinics. One of the problems is the lack of proper calibration between the robotic manipulator and appropriate imaging device. In this work, we developed a flexible framework for hand-eye calibration of an ophthalmic robot with a microscope-integrated Optical Coherence Tomography (MI-OCT) without any markers. The proposed method ...

      Read Full Article
    16. Automated Layer Segmentation of Retinal Optical Coherence Tomography Images Using a Deep Feature Enhanced Structured Random Forests Classifier

      Automated Layer Segmentation of Retinal Optical Coherence Tomography Images Using a Deep Feature Enhanced Structured Random Forests Classifier

      Optical coherence tomography (OCT) is a high-resolution and non-invasive imaging modality that has become one of the most prevalent techniques for ophthalmic diagnosis. Retinal layer segmentation is very crucial for doctors to diagnose and study retinal diseases. However, manual segmentation is often a time-consuming and subjective process. In this work, we propose a new method for automatically segmenting retinal OCT images, which integrates deep features and hand-designed features to train a structured random forests classifier. The deep convolutional features are learned from deep residual network. With the trained classifier, we can get the contour probability graph of each layer, finally ...

      Read Full Article
    17. Surrogate-assisted Retinal OCT Image Classification Based on Convolutional Neural Networks

      Surrogate-assisted Retinal OCT Image Classification Based on Convolutional Neural Networks

      Optical Coherence Tomography (OCT) is becoming one of the most important modalities for the noninvasive assessment of retinal eye diseases. As the number of acquired OCT volumes increases, automating the OCT image analysis is becoming increasingly relevant. In this paper, we propose a surrogate-assisted classification method to classify retinal OCT images automatically based on convolutional neural networks (CNNs). Image denoising is first performed to reduce the noise. Thresholding and morphological dilation are applied to extract the masks. The denoised images and the masks are then employed to generate a lot of surrogate images, which are used to train the CNN ...

      Read Full Article
    18. Optimized Optical Coherence Tomography Imaging With Hough Transform-Based Fixed-Pattern Noise Reduction

      Optimized Optical Coherence Tomography Imaging With Hough Transform-Based Fixed-Pattern Noise Reduction

      Fixed-pattern noise seriously affects the clinical application of optical coherence tomography (OCT), especially, in the imaging of tumorous tissue. We propose a Hough transform-based fixed-pattern noise reduction (HTFPNR) method to reduce the fixed-pattern noise for optimizing imaging of tumorous tissue with OCT system. Using by the HTFPNR method, we detect and map the outline of fixed-pattern noise in the OCT images, and finally efficiently reduce the fixed-pattern noise by the longitudinal and horizontal intelligent processing procedure. We adopt the image-to-noise ratio with full information (INRfi) and the noise reduction ratio (NRR) to evaluate the outcome of fixed-pattern noise reduction ratio ...

      Read Full Article
    19. Optimized Automated Segmentation and 3D Reconstruction Using Intracoronary Optical Coherence Tomography

      Optimized Automated Segmentation and 3D Reconstruction Using Intracoronary Optical Coherence Tomography

      Real time segmentation and three-dimensional (3D) reconstruction of the coronary arteries is challenging and limited by the increased computational time of the developed computer-aided methods. We present a novel and time-efficient method for intracoronary lumen detection which produces 3D coronary arteries using Optical Coherence Tomographic (OCT) images. OCT images are acquired for multiple patients and longitudinal cross-section (LOCS) images are reconstructed using different acquisition angles. The lumen contours for each LOCS image are extracted and translated to 2D cross-sectional images. Using two angiographic projections the centerline of the coronary vessel is reconstructed in 3D and the detected 2D contours are ...

      Read Full Article
    20. Common-path Optical Coherence Tomography using Bessel Beam from Negative Axicon Optical Fiber Tip

      Common-path Optical Coherence Tomography using Bessel Beam from Negative Axicon Optical Fiber Tip

      In this work a deep-seated negative axicon fiber tip (DSNA-FT) generating Bessel-Gauss beam is proposed as an optical probe for common-path optical coherence tomography (CPOCT) imaging. The axicon at the optical fiber tip is fabricated by etching the tip of a selective optical fiber in hydrofluoric acid under the influence of capillary action. The non-diffracting type quasi Bessel beam from the DSNA-FT having a long depth of field, ~0.7 mm, is used for CPOCT imaging of different type of samples i.e. sticky tape, fish scale, and rice grain. The CPOCT with unique and simple optical fiber probe has ...

      Read Full Article
    21. Use of Optical Clearing Agents for Imaging Root Surfaces With Optical Coherence Tomography

      Use of Optical Clearing Agents for Imaging Root Surfaces With Optical Coherence Tomography

      The diagnosis of root caries and root fractures is of increasing importance due to our aging population. The objective of this study is to show that optical clearing agents can be used to increase the visibility of subsurface structures in tooth roots to aid in the diagnosis of root caries depth and extension and to differentiate from subsurface defects. Previous studies have shown that high refractive index fluids can increase the depth penetration of optical coherence tomography (OCT) for imaging caries lesions on tooth enamel. Extracted teeth with suspected root caries were imaged with (OCT) with and without the addition ...

      Read Full Article
    22. Real-time digital signal processing-based optical coherence tomography and Doppler optical coherence tomography

      Real-time digital signal processing-based optical coherence tomography and Doppler optical coherence tomography

      We present the development and use of a real-time digital signal processing (DSP)-based optical coherence tomography (OCT) and Doppler OCT system. Images of microstructure and transient fluid-flow profiles are acquired using the DSP architecture for real-time processing of computationally intensive calculations. This acquisition system is readily configurable for a wide range of real-time signal processing and image processing applications in OCT.

      Read Full Article
    23. Viscosity monitoring during hemodiluted blood coagulation using optical coherence elastography

      Viscosity monitoring during hemodiluted blood coagulation using optical coherence elastography

      Rapid and accurate clot diagnostic systems are needed for the assessment of hemodiluted blood coagulation. We develop a real-time optical coherence elastography (OCE) system, which measures the attenuation coefficient of a compressional wave induced by a piezoelectric transducer (PZT) in a drop of blood using optical coherence tomography (OCT), for the determination of viscous properties during the dynamic whole blood coagulation process. Changes in the viscous properties increase the attenuation coefficient of the sample. Consequently, dynamic blood coagulation status can be monitored by relating changes of the attenuation coefficient to clinically relevant coagulation metrics, including the initial coagulation time and ...

      Read Full Article
    24. A New Framework for the Integrative Analytics of Intravascular Ultrasound and Optical Coherence Tomography Images

      A New Framework for the Integrative Analytics of Intravascular Ultrasound and Optical Coherence Tomography Images

      The integrative analysis of multimodal medical images plays an important role in the diagnosis of coronary artery disease by providing additional comprehensive information that cannot be found in an individual source image. Intravascular Ultrasound (IVUS) and Optical Coherence Tomography (IV-OCT) are two imaging modalities that have been widely used in the medical practice for the assessment of arterial health and the detection of vascular lumen lesions. IV-OCT has a high resolution and poor penetration, while IVUS has a low resolution and high detection depth. This paper proposes a new approach for the fusion of intravascular ultrasound and optical coherence tomography ...

      Read Full Article
    1-24 of 292 1 2 3 4 ... 11 12 13 »
  1. Categories

    1. Applications:

      Art, Cardiology, Dentistry, Dermatology, Developmental Biology, Gastroenterology, Gynecology, Microscopy, NDE/NDT, Neurology, Oncology, Ophthalmology, Other Non-Medical, Otolaryngology, Pulmonology, Urology
    2. Business News:

      Acquisition, Clinical Trials, Funding, Other Business News, Partnership, Patents
    3. Technology:

      Broadband Sources, Probes, Tunable Sources
    4. Miscellaneous:

      Jobs & Studentships, Student Theses, Textbooks