1. Articles from scott e. fraser

    1-23 of 23
    1. 3D in vivo imaging with extended-focus optical coherence microscopy

      3D in vivo imaging with extended-focus optical coherence microscopy

      Optical coherence microscopy (OCM) has unique advantages of non-invasive 3D imaging without the need of exogenous labels for studying biological samples. However, the imaging depth of this technique is limited by the tradeoff between the depth of focus (DOF) and high lateral resolution in Gaussian optics. To overcome this limitation, we have developed an extended-focus OCM (xf-OCM) imaging system using quasi-Bessel beam illumination to extend the DOF to ∼100 μm, about 3-fold greater than standard OCM. High lateral resolution of 1.6 μm ensured detailed identification of structures within live animal samples. The insensitivity to spherical aberrations strengthened the capability ...

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    2. Optical coherence microscopy with extended focus for in vivo embryonic imaging

      Optical coherence microscopy with extended focus for in vivo embryonic imaging

      Optical coherence microscopy (OCM) has unique advantages of high-resolution volumetric imaging without relying on exogenous labels or dyes. It combines the coherence-gated depth discrimination of optical coherence tomography (OCT) with the high lateral resolution of confocal microscopy, offering an excellent balance between the resolutions and imaging depth. However, as the lateral resolution becomes higher, the imaging depth of OCM decreases and its three-dimensional imaging capability is greatly degraded. To overcome this limitation, we used amplitude apodization to create quasi-Bessel beam illumination in order to extend the depth of focus. The lateral and axial resolutions of our OCM system were measured ...

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    3. Phase variance optical coherence microscopy for label-free imaging of the developing vasculature in zebrafish embryos

      Phase variance optical coherence microscopy for label-free imaging of the developing vasculature in zebrafish embryos

      A phase variance optical coherence microscope (pvOCM) has been created to image blood flow in the microvasculature of zebrafish embryos, without the use of exogenous labels. The pvOCM imaging system has axial and lateral resolutions of 2.8    μ m 2.8  μm in tissue and imaging depth of more than 100    μ m 100  μm . Images of 2 to 5 days postfertilization zebrafish embryos identified the detailed anatomical structure based on OCM intensity contrast. Phase variance contrast offered visualization of blood flow in the arteries, veins, and capillaries. The pvOCM images of the vasculature were confirmed by direct comparisons with fluorescence ...

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    4. Label-free imaging of developing vasculature in zebrafish with phase variance optical coherence microscopy

      Label-free imaging of developing vasculature in zebrafish with phase variance optical coherence microscopy

      A phase variance optical coherence microscope (pvOCM) has been created to visualize blood flow in the vasculature of zebrafish embryos, without using exogenous labels. The pvOCM imaging system has axial and lateral resolutions of 2 μm in tissue, and imaging depth of more than 100 μm. Imaging of 2–5 days post-fertilization zebrafish embryos identified the detailed structures of somites, spinal cord, gut and notochord based on intensity contrast. Visualization of the blood flow in the aorta, veins and intersegmental vessels was achieved with phase variance contrast. The pvOCM vasculature images were confirmed with corresponding fluorescence microscopy of a zebrafish ...

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    5. Optical Coherence Tomography System For Health Characterization Of An Eye

      Optical Coherence Tomography System For Health Characterization Of An Eye

      This disclosure relates to the field of Optical Coherence Tomography (OCT). This disclosure particularly relates to methods and systems for providing larger field of view OCT images. This disclosure also particularly relates to methods and systems for OCT angiography. This disclosure further relates to systems for health characterization of an eye by OCT angiography.

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    6. Extended Duration Optical Coherence Tomography (OCT) System

      Extended Duration Optical Coherence Tomography (OCT) System

      This disclosure relates to the field of Optical Coherence Tomography (OCT). This disclosure particularly relates to methods and systems for providing larger field of view OCT images. This disclosure also particularly relates to methods and systems for OCT angiography. These systems may allow OCT scanning for an extended duration and generation of large field OCT images suitable for the OCT angiography.

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    7. Optical Coherence Tomography (OCT) System With PHASE-SENSITIVE B-SCAN Registration

      Optical Coherence Tomography (OCT) System With PHASE-SENSITIVE B-SCAN Registration

      This disclosure relates to the field of Optical Coherence Tomography (OCT). This disclosure particularly relates to an OCT system having a configuration that uses a phase sensitive B-scan registration method. In this disclosure, an OCT system may have a configuration that scans a physical object, acquires OCT signals to form B-scans, uses these B-scans to determine an optimal shift in an axial direction by using total phase error between B-scans, and align B-scans, thereby minimizing effects of motion that may occur during scanning of the physical object. La présente invention concerne le domaine de la tomographie par cohérence ...

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    8. Optical Coherence Tomography (OCT) System With Improved Motion Contrast

      Optical Coherence Tomography (OCT) System With Improved Motion Contrast

      This disclosure relates to the field of Optical Coherence Tomography (OCT). This disclosure particularly relates to an OCT system with improved motion contrast. This disclosure particularly relates to motion contrast methods for such OCT systems.

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    9. Detection of PED vascularization using phase-variance OCT angiography

      Detection of PED vascularization using phase-variance OCT angiography

      Purpose: To demonstrate the use of phase-variance optical coherence tomography (PV-OCT) angiography for detection of pigment epithelial detachment (PED) vascularization in age-related macular degeneration (AMD). Patients and methods: Patients with PEDs and exudative AMD were evaluated by the Retina Services at the University of California, Davis, and the University of California, San Francisco. Each subject underwent fluorescein angiography and structural optical coherence tomography (OCT). Phase-variance OCT analysis was used to create angiographic images of the retinal and choroidal vasculature. PV-OCT-generated B-scans were superimposed on structural OCT B-scans to allow easy identification of perfused vascular structures. Results: Three patients with vascularized ...

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    10. Phase-Variance Optical Coherence Tomography: A New Technique for Noninvasive Angiography

      Phase-Variance Optical Coherence Tomography: A New Technique for Noninvasive Angiography

      Purpose Phase-variance optical coherence tomography (PV-OCT) provides volumetric imaging of the retinal vasculature without the need for intravenous injection of a fluorophore. We compare images from PV-OCT and fluorescein angiography (FA) for normal individuals and patients with age-related macular degeneration (AMD) and diabetic retinopathy. Design This is an evaluation of a diagnostic technology. Participants Four patients underwent comparative retinovascular imaging using FA and PV-OCT. Imaging was performed on 1 normal individual, 1 patient with dry AMD, 1 patient with exudative AMD, and 1 patient with nonproliferative diabetic retinopathy. Methods Fluorescein angiography imaging was performed using a Topcon Corp (Tokyo, Japan ...

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    11. Optical imaging of the chorioretinal vasculature in the living human eye

      Optical imaging of the chorioretinal vasculature in the living human eye

      Detailed visualization of microvascular changes in the human retina is clinically limited by the capabilities of angiography imaging, a 2D fundus photograph that requires an intravenous injection of fluorescent dye. Whereas current angiography methods enable visualization of some retinal capillary detail, they do not adequately reveal the choriocapillaris or other microvascular features beneath the retina. We have developed a noninvasive microvascular imaging technique called phase-variance optical coherence tomography (pvOCT), which identifies vasculature three dimensionally through analysis of data acquired with OCT systems. The pvOCT imaging method is not only capable of generating capillary perfusion maps for the retina, but it ...

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    12. Visualization of human retinal and choroidal vascular networks with phase-variance optical coherence tomography

      Visualization of human retinal and choroidal vascular networks with phase-variance optical coherence tomography

      We present in vivo noninvasive retinal and choroidal perfusion maps with phase-variance optical coherence tomography (pvOCT). We acquired a pvOCT volumetric data set of a normal subject and visualized blood circulation in the retina and the choroid. En face projection views of the retina as well as the choroid were generated from a manually segmented volumetric data set. In addition, the processed pvOCT images were compared to current standard imaging modalities used for retinal and choroidal vasculature visualization in clinical settings, including fluorescein angiography (FA) and indocyanine green angiography (ICGA).

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    13. Enhanced Optical Angiography Using Intensity Contrast And Phase Contrast Imaging Methods

      Enhanced Optical Angiography Using Intensity Contrast And Phase Contrast Imaging Methods

      The methods described herein are methods to ascertain motion contrast within optical coherence tomography data based upon intensity. The methods of the invention use logarithm operation to convert the multiplicative amplitude or intensity fluctuations (speckle) into the additive variations and recovers the motion contrasts by removing the speckle free signals (static regions) through statistical analysis.

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    14. In Vivo Human Choroidal Vascular Pattern Visualization Using High-Speed Swept-Source Optical Coherence Tomography at 1060 nm

      In Vivo Human Choroidal Vascular Pattern Visualization Using High-Speed Swept-Source Optical Coherence Tomography at 1060 nm

      Purpose. To investigate the retinal and choroidal vascular pattern, structure, and thickness using high-speed, high axial resolution, swept-source optical coherence tomography (SS-OCT) at 1060 nm, demonstrating enhanced penetration through all choroidal layers. Methods. An ophthalmic SS-OCT system was developed operating at 57,000 A-lines/s with 5.9 μm axial resolution and was used to collect 3D images with scanning angles up to ~70° x 35°. The similar features were observed in the choroidal layers by imaging three healthy volunteers. En face images, extracted at different depths, capture features of the retinal and choroidal vasculature networks and substructure. Retinal and ...

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    15. Differential phase-contrast, swept-source optical coherence tomography at 1060 nm for in vivo human retinal and choroidal vasculature visualization

      Differential phase-contrast, swept-source optical coherence tomography at 1060 nm for in vivo human retinal and choroidal vasculature visualization

      Human retinal and choroidal vasculature was visualized by a differential phase-contrast (DPC) method using high-speed, swept-source optical coherence tomography (SS-OCT) at 1060 nm. The vasculature was recognized as regions of motion by creating differential phase-variance (DPV) tomograms: multiple B-scans of individual slices through the retina were collected and the variance of the phase differences was calculated. DPV captured the small vessels and the meshwork of capillaries associated with the inner retina in en-face images over 4  mm2. The swept-source laser at 1060 nm offered the needed phase sensitivity to perform DPV and generated en-face images that capture motion in the ...

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    16. Visualization of human retinal capillary networks: a comparison of intensity, speckle-variance and phase-variance optical coherence tomography

      Visualization of human retinal capillary networks: a comparison of intensity, speckle-variance and phase-variance optical coherence tomography

      We evaluate methods to visualize human retinal micro-circulation in vivo by standard intensity-based optical coherence tomography (OCT), speckle-variance optical coherence tomography (svOCT), and phase-variance optical coherence tomography (pvOCT). En face projection views created from the same volumetric data set of the human retina using all three data processing methods are created and compared. Additionally we used support vector machine (SVM) based semi-automatic segmentation to generate en face projection views of individual retinal layers. The layers include: first, the whole inner retina (from the nerve fiber layer to the outer nuclear layer), and second, from the ganglion cell layer to the ...

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    17. Noninvasive Imaging of the Foveal Avascular Zone with High-Speed, Phase-Variance Optical Coherence Tomography

      Noninvasive Imaging of the Foveal Avascular Zone with High-Speed, Phase-Variance Optical Coherence Tomography

      Purpose. To demonstrate the application of phase-variance optical coherence tomography (pvOCT) for contrast agent–free in vivo imaging of volumetric retinal microcirculation in the human foveal region and for extraction of foveal avascular zone dimensions. Methods. A custom-built, high-speed Fourier-domain OCT retinal imaging system was used to image retinas of two healthy subjects and eight diabetic patients. Through the acquisition of multiple B-scans for each scan location, phase differences between consecutive scans were extracted and used for phase-variance contrast, identifying motion signals from within blood vessels and capillaries. The en face projection view of the inner retinal layers segmented out ...

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    18. Dynamic motion contrast and transverse flow estimation using optical coherence tomography

      Dynamic motion contrast and transverse flow estimation using optical coherence tomography
      The methods described herein are methods to ascertain motion contrast within optical coherence tomography data based upon phase variance. The phase variance contrast observes the nanometer scale motion of scatterers associated with Brownian motion and other non-flow motion. The inventive method of calculating motion contrast from the phase variance can differentiate regions of different mobility based on the motion contrast differences, and can use the phase information to characterize mobility properties of the scatterers. In flow regions, the inventive method for acquiring and analyzing motion contrast can identify the regions as well as characterize the motion. Furthermore, the inventive method ...
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    19. In vivo volumetric imaging of human retinal circulation with phase-variance optical coherence tomography

      In vivo volumetric imaging of human retinal circulation with phase-variance optical coherence tomography
      We present in vivo volumetric images of human retinal micro-circulation using Fourier-domain optical coherence tomography (Fd-OCT) with the phase-variance based motion contrast method. Currently fundus fluorescein angiography (FA) is the standard technique in clinical settings for visualizing blood circulation of the retina. High contrast imaging of retinal vasculature is achieved by injection of a fluorescein dye into the systemic circulation. We previously reported phase-variance optical coherence tomography (pvOCT) as an alternative and non-invasive technique to image human retinal capillaries. In contrast to FA, pvOCT allows not only noninvasive visualization of a two-dimensional retinal perfusion map but also volumetric morphology of ...
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    20. Visualization of human retinal micro-capillaries with phase contrast high-speed optical coherence tomography

      Visualization of human retinal micro-capillaries with phase contrast high-speed optical coherence tomography

      We present high-speed Fourier-domain optical coherence tomography (Fd-OCT) with the phase variance based motion contrast method for visualizing retinal micro-circulation in vivo. This technique allows non-invasive visualization of a two-dimensional retinal perfusion map and concurrent volumetric morphology of retinal microvasculature with high sensitivity. The high-speed acquisition rate at 125kHz A-scans enables reduction of motion artifacts with increased scanning area if compared to previously reported results. Several scanning schemes with different sampling densities and scanning areas are evaluated to find optimal parameters for in vivo imaging. In order to evaluate this technique, we compare OCT micro-capillary imaging using the phase variance ...

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    21. Volumetric microvascular imaging of human retina using optical coherence tomography with a novel motion contrast technique

      Volumetric microvascular imaging of human retina using optical coherence tomography with a novel motion contrast technique
      Phase variance-based motion contrast imaging is demonstrated using a spectral domain optical coherence tomography system for the in vivo human retina. This contrast technique spatially identifies locations of motion within the retina primarily associated with vasculature. Histogrambased noise analysis of the motion contrast images was used to reduce the motion noise created by transverse eye motion. En face summation images created from the 3D motion contrast data are presented with segmentation of selected retinal layers to provide non-invasive vascular visualization comparable to currently used invasive angiographic imaging. This motion contrast technique has demonstrated the ability to visualize resolutionlimited vasculature independent ...
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    22. Phase-Contrast OCT Imaging of Transverse Flows in the Mouse Retina and Choroid

      PURPOSE. To test the hypothesis that a novel phase-contrast optical coherence tomography (OCT) system can image retinal and choroidal vessels in the living mouse. METHODS. A high-speed spectral domain optical coherence tomography (SDOCT) system, which measures the reflections for the entire depth of the retina at once with each axial scan (A-scan), was developed for mouse retinal imaging. Acquiring multiple A-scans over a transverse line across the mouse retina offers a two-dimensional cross-sectional image (B-scan); several neighboring B-scans can be assembled into a three-dimensional OCT image. To visualize mobility and transverse flow in retinal vessels, the statistical variance of phase ...
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    23. Dynamic Motion Contrast and Transferse Flow Estimates using Optical Coherence Tomography

      Dynamic Motion Contrast and Transferse Flow Estimates using Optical Coherence Tomography
      (WO/2008/002839) DYNAMIC MOTION CONTRAST AND TRANSVERSE FLOW ESTIMATION USING OPTICAL COHERENCE TOMOGRAPHY CALIFORNIA INSTITUTE OF TECHNOLOGY [US/US]; M/C 210-85, 1200 East California Blvd., Pasadena, CA 91125 (US) (All Except US). THE REGENTS OF THE UNIVERSITY OF CALIFORNIA [US/US]; 1111 Franklin Street, 12th Floor, Oakland, California 94607 (US) (All Except US). FINGLER, Jeffrey, P. [US/US]; 411 South Madison Avenue, Apt. 101, Pasadena, California 91101 (US) (US Only). FRASER, Scott, E. [US/US
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    1-23 of 23
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    1. (23 articles) Scott E. Fraser
    2. (16 articles) California Institute of Technology
    3. (10 articles) Daniel M. Schwartz
    4. (9 articles) University of Southern California
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    Dynamic Motion Contrast and Transferse Flow Estimates using Optical Coherence Tomography Volumetric microvascular imaging of human retina using optical coherence tomography with a novel motion contrast technique Visualization of human retinal micro-capillaries with phase contrast high-speed optical coherence tomography In vivo volumetric imaging of human retinal circulation with phase-variance optical coherence tomography Noninvasive Imaging of the Foveal Avascular Zone with High-Speed, Phase-Variance Optical Coherence Tomography Visualization of human retinal capillary networks: a comparison of intensity, speckle-variance and phase-variance optical coherence tomography Differential phase-contrast, swept-source optical coherence tomography at 1060 nm for in vivo human retinal and choroidal vasculature visualization Optical imaging of the chorioretinal vasculature in the living human eye Phase-Variance Optical Coherence Tomography: A New Technique for Noninvasive Angiography 3D in vivo imaging with extended-focus optical coherence microscopy The Evolution of the Plateau, an Optical Coherence Tomography Signature Seen in Geographic Atrophy Imaging collector channel entrance with a new intraocular micro-probe swept-source optical coherence tomography