1. Articles from lin an

    1-24 of 35 1 2 »
    1. Comparison Between Spectral-Domain and Swept-Source Optical Coherence Tomography Angiographic Imaging of Choroidal Neovascularization

      Comparison Between Spectral-Domain and Swept-Source Optical Coherence Tomography Angiographic Imaging of Choroidal Neovascularization

      Purpose : The purpose of this study was to compare imaging of choroidal neovascularization (CNV) using swept-source (SS) and spectral-domain (SD) optical coherence tomography angiography (OCTA). Methods : Optical coherence tomography angiography was performed using a 100-kHz SS-OCT instrument and a 68-kHz SD-OCTA instrument (Carl Zeiss Meditec, Inc.). Both 3 × 3- and 6 × 6-mm 2 scans were obtained on both instruments. The 3 × 3-mm 2 SS-OCTA scans consisted of 300 A-scans per B-scan at 300 B-scan positions, and the SD-OCTA scans consisted of 245 A-scans at 245 B-scan positions. The 6 × 6-mm 2 SS-OCTA scans consisted of 420 A-scans per B-scan at ...

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    2. Projection Artifact Removal Improves Visualization and Quantitation of Macular Neovascularization Imaged by Optical Coherence Tomography Angiography

      Projection Artifact Removal Improves Visualization and Quantitation of Macular Neovascularization Imaged by Optical Coherence Tomography Angiography

      Purpose To visualize and quantify the size and vessel density of macular neovascularization (MNV) using optical coherence tomography angiography (OCTA) with a projection artifact removal algorithm. Design Multicenter, observational study. Participants Subjects with MNV in ≥1 eye. Methods Patients were imaged using either a swept-source OCTA prototype system or a spectral-domain OCTA prototype system. The optical microangiography (OMAG) algorithm was used to generate the OCTA images. Projection artifacts from the overlying retinal circulation were removed from the OMAG OCTA images using a novel algorithm. After removal of the projection artifacts from the OCTA images, we assessed the size and vascularity ...

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    3. Optical Coherence Tomography Angiography of Asymptomatic Neovascularization in Intermediate Age-Related Macular Degeneration

      Optical Coherence Tomography Angiography of Asymptomatic Neovascularization in Intermediate Age-Related Macular Degeneration

      Purpose To determine whether angiography with swept-source (SS) optical coherence tomography (OCT) identifies subclinical type 1 neovascularization in asymptomatic eyes with intermediate age-related macular degeneration (iAMD). Design Prospective, observational, consecutive case series. Participants Patients with asymptomatic iAMD in one eye and neovascular age-related macular degeneration (AMD) in their fellow eye. Methods The patients underwent SS OCT angiography (OCTA), fluorescein angiography (FA), and indocyanine green angiography (ICGA), and the images from these 3 angiographic techniques were compared. Main Outcome Measures Identification of subclinical type 1 neovascularization with SS OCTA in asymptomatic eyes with iAMD. Results Eleven consecutive patients with iAMD in ...

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    4. SWEPT SOURCE OCT ANGIOGRAPHY OF NEOVASCULAR MACULAR TELANGIECTASIA TYPE 2

      SWEPT SOURCE OCT ANGIOGRAPHY OF NEOVASCULAR MACULAR TELANGIECTASIA TYPE 2

      Background/Purpose: To image subretinal neovascularization in proliferative macular telangiectasia Type 2 (MacTel2) using swept source optical coherence tomography based microangiography (OMAG). Methods: Patients with macular telangiectasia Type 2 were enrolled in a prospective, observational study known as the MacTel Project and evaluated using a high-speed 1,050 nm swept-source OCT prototype system. The OMAG algorithm generated en face flow images from three retinal layers, and the region bounded by the outer retina and Bruch membrane, the choriocapillaris, and the remaining choroidal vasculature. The en face OMAG images were compared with images from fluorescein angiography and indocyanine green angiography. Results ...

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    5. Noninvasive Visualization and Analysis of the Human Parafoveal Capillary Network Using Swept Source OCT Optical Microangiography

      Noninvasive Visualization and Analysis of the Human Parafoveal Capillary Network Using Swept Source OCT Optical Microangiography

      Purpose. We characterized the foveal avascular zone (FAZ) and the parafoveal capillary network in healthy subjects using swept source OCT optical microangiography (OMAG). Methods. We acquired OMAG images of the macula of 19 eyes (13 healthy individuals) using a prototype swept source laser OCT. En face images of the retinal vasculature were generated for superficial and deep inner retinal layers (SRL/DRL) in regions of interest 250 (ROI-250) and 500 (ROI-500) μm from the FAZ border. Results. The mean area (mm 2 ) of the FAZ was 0.304 ± 0.132 for the SRL and 0.486 ± 0.162 for the ...

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    6. Wide-field imaging of retinal vasculature using optical coherence tomography-based microangiography provided by motion tracking.

      Wide-field imaging of retinal vasculature using optical coherence tomography-based microangiography provided by motion tracking.

      Optical coherence tomography (OCT)-based optical microangiography (OMAG) is a high-resolution, noninvasive imaging technique capable of providing three-dimensional in vivo blood flow visualization within microcirculatory tissue beds in the eye. Although the technique has demonstrated early clinical utility by imaging diseased eyes, its limited field of view (FOV) and the sensitivity to eye motion remain the two biggest challenges for the widespread clinical use of the technology. Here, we report the results of retinal OMAG imaging obtained from a Zeiss Cirrus 5000 spectral domain OCT system with motion tracking capability achieved by a line scan ophthalmoscope (LSO). The tracking LSO ...

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    7. Imaging Areas of Retinal Nonperfusion in Ischemic Branch Retinal Vein Occlusion With Swept-Source OCT Microangiography

      Imaging Areas of Retinal Nonperfusion in Ischemic Branch Retinal Vein Occlusion With Swept-Source OCT Microangiography

      The authors present the case of a patient with a history of ischemic branch vein occlusion and multimodal imaging of the retinal vasculature by fluorescein angiography (FA) and ultrahigh-speed swept-source optical coherence tomography (SS-OCT) microangiography (SS-OCT laser prototype; 1,050 nm, 100,000 A-scans/second). Multiple images across the macula were acquired (3 × 3 mm cubes in clusters of four repeated B-scans). En face images of the vasculature were generated by implementing an intensity differentiation algorithm. The retinal vasculature as well areas of nonperfusion could be identified precisely at multiple retinal levels. Ultrahigh-speed SS-OCT microangiography provides noninvasive, three-dimensional, high-resolution images ...

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    8. Swept-Source OCT Angiography of Macular Telangiectasia Type 2

      Swept-Source OCT Angiography of Macular Telangiectasia Type 2

      BACKGROUND AND OBJECTIVE: To evaluate the central macular microvascular network in patients with macular telangiectasia type 2 (MacTel2) using optical coherence tomography (OCT)-based microangiography (OMAG). PATIENTS AND METHODS: Prospective, observational study of patients with MacTel2 evaluated using a swept-source OCT (SS-OCT) prototype. OMAG was performed using a 3 mm × 3 mm central foveal raster scan. The algorithm segmented the retina into three layers. Microvascular distribution was depicted as en face images, and qualitative information was compared to fluorescein angiography (FA) images. RESULTS: OMAG detected abnormal microvasculature in all MacTel2 eyes, predominantly in the middle retinal layers with neovascularization in ...

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    9. Swept-Source OCT Angiography of the Retinal Vasculature Using Intensity Differentiation-based Optical Microangiography Algorithms

      Swept-Source OCT Angiography of the Retinal Vasculature Using Intensity Differentiation-based Optical Microangiography Algorithms

      To demonstrate the feasibility of using a 1,050-nm swept-source optical coherence tomography (SS-OCT) system to achieve noninvasive retinal vasculature imaging in human eyes. MATERIALS AND METHODS: Volumetric data sets were acquired using a 1-µm SS-OCT prototype that operated at a 100-kHz A-line rate. A scanning protocol designed to allow for motion contrast processing, referred to as OCT angiography or optical microangiography (OMAG), was used to scan an approximately 3 × 3–mm area in the central macular region of the retina within approximately 4.5 seconds. An intensity differentiation-based OMAG algorithm was used to extract three-dimensional retinal functional microvasculature ...

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    10. Method and apparatus for quantitative imaging of blood perfusion in living tissue

      Method and apparatus for quantitative imaging of blood perfusion in living tissue

      Embodiments provide methods and systems for quantitative imaging of blood perfusion in living tissue. A method provides for obtaining an optical microangiography (OMAG) image of a sample, wherein the image has an OMAG background sample; digitally reconstructing a homogeneous ideal static background tissue; replacing the OMAG background sample with the digitally reconstructed homogeneous ideal static background tissue; correlating two or more neighboring A-lines with the digitally reconstructed homogeneous ideal static background tissue; and measuring a phase difference between the two or more neighboring A-lines to quantify blood perfusion in the sample. Methods using digital reconstruction to reduce random phase noise ...

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    11. Noninvasive imaging of pulsatile movements of the optic nerve head in normal human subjects using phase-sensitive spectral domain optical coherence tomography

      Noninvasive imaging of pulsatile movements of the optic nerve head in normal human subjects using phase-sensitive spectral domain optical coherence tomography

      We report use of high-speed spectral domain optical coherence tomography to noninvasively image pulsatile axial movement of the optic nerve head (ONH) in normal human subjects. Time-lapse B-scan mode is used to image the ONH at 500 frames per second. Capture of phase differences between adjacent B-scans permits extraction of axial ONH movement. We find the ONH experiences continuous oscillatory axial motion that is strongly correlated with simultaneously measured pulsatile blood flow in the central retinal artery.

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    12. High-resolution 1050 nm spectral domain retinal optical coherence tomography at 120 kHz A-scan rate with 6.1 mm imaging depth

      High-resolution 1050 nm spectral domain retinal optical coherence tomography at 120 kHz A-scan rate with 6.1 mm imaging depth

      We report a newly developed high speed 1050nm spectral domain optical coherence tomography (SD-OCT) system for imaging posterior segment of human eye. The system is capable of an axial resolution at ~10 µm in air, an imaging depth of 6.1 mm in air, a system sensitivity fall-off at ~6 dB/3mm and an imaging speed of 120,000 A-scans per second. We experimentally demonstrate the system’s capability to perform phase-resolved imaging of dynamic blood flow within retina, indicating high phase stability of the SDOCT system. Finally, we show an example that uses this newly developed system to image ...

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    13. Extended imaging depth to 12 mm for 1050-nm spectral domain optical coherence tomography for imaging the whole anterior segment of the human eye at 120-kHz A-scan rate

      Extended imaging depth to 12 mm for 1050-nm spectral domain optical coherence tomography for imaging the whole anterior segment of the human eye at 120-kHz A-scan rate

      We demonstrate a 1050-nm spectral domain optical coherence tomography (OCT) system with a 12 mm imaging depth in air, a 120 kHz A-scan rate and a 10 μm axial resolution for anterior-segment imaging of human eye, in which a new prototype InGaAs linescan camera with 2048 active-pixel photodiodes is employed to record OCT spectral interferograms in parallel. Combined with the full-range complex technique, we show that the system delivers comparable imaging performance to that of a swept-source OCT with similar system specifications.

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    14. Optical microangiography provides correlation between microstructure and microvasculature of optic nerve head in human subjects

      Optical microangiography provides correlation between microstructure and microvasculature of optic nerve head in human subjects

      It is demonstrated that optical microangiography (OMAG) is capable of imaging the detailed microstructure and microvasculature of the in vivo human optic nerve head (ONH), including the prelaminar tissue, the lamina cribrosa, the scleral rim and the vessels in the region of the circle of Zin-Haller. For demonstration, an ultrahigh sensitive OMAG system operating in the 850 nm wavelength region and a 500 kHz A-scan rate resulting in a spatial resolution of ∼ 6     μ m were used. It was shown that OMAG provides superior results for three-dimensional imaging of the ONH compared to conventional optical coherence tomography by simultaneously recording both ...

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    15. Quantifying Optical Microangiography Images Obtained from a Spectral Domain Optical Coherence Tomography System

      Quantifying Optical Microangiography Images Obtained from a Spectral Domain Optical Coherence Tomography System

      The blood vessel morphology is known to correlate with several diseases, such as cancer, and is important for describing several tissue physiological processes, like angiogenesis. Therefore, a quantitative method for characterizing the angiography obtained from medical images would have several clinical applications. Optical microangiography (OMAG) is a method for obtaining three-dimensional images of blood vessels within a volume of tissue. In this study we propose to quantify OMAG images obtained with a spectral domain optical coherence tomography system. A technique for determining three measureable parameters (the fractal dimension, the vessel length fraction, and the vessel area density) is proposed and ...

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    16. Automated segmentation of intramacular layers in Fourier domain optical coherence tomography structural images from normal subjects

      Automated segmentation of intramacular layers in Fourier domain optical coherence tomography structural images from normal subjects

      Segmentation of optical coherence tomography (OCT) cross-sectional structural images is important for assisting ophthalmologists in clinical decision making in terms of both diagnosis and treatment. We present an automatic approach for segmenting intramacular layers in Fourier domain optical coherence tomography (FD-OCT) images using a searching strategy based on locally weighted gradient extrema, coupled with an error-removing technique based on statistical error estimation. A two-step denoising preprocess in different directions is also employed to suppress random speckle noise while preserving the layer boundary as intact as possible. The algorithms are tested on the FD-OCT volume images obtained from four normal subjects ...

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    17. Using ultrahigh sensitive optical microangiography to achieve comprehensive depth resolved microvasculature mapping for human retina

      Using ultrahigh sensitive optical microangiography to achieve comprehensive depth resolved microvasculature mapping for human retina

      Lin An, Tueng T. Shen, and Ruikang K. Wang This paper presents comprehensive and depth-resolved retinal microvasculature images within human retina achieved by a newly developed ultrahigh sensitive optical microangiography (UHS-OMAG) system. Due to its high flow sensitivity, UHS-OMAG is much more sensitive to tissue motion due to the involun ... [J. Biomed. Opt. 16, 106013 (2011)] published Mon Oct 24, 2011.

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    18. In vivo microstructural and microvascular imaging of the human corneo-scleral limbus using optical coherence tomography

      In vivo microstructural and microvascular imaging of the human corneo-scleral limbus using optical coherence tomography

      The corneo-scleral limbus contains several biological components, which are important constituents for understanding, diagnosing and managing several ocular pathologies, such as glaucoma and corneal abnormalities. An anterior segment optical coherence tomography (AS-OCT) system integrated with optical microangiography (OMAG) is used in this study to non-invasively visualize the three-dimensional microstructural and microvascular properties of the limbal region. Advantages include first the ability to correct optical distortion of microstructural images enabling quantification of relationships in the anterior chamber angle. Second, microvascular images enable the visualization of the microcirculation in the limbal area without the use of exogenous contrast agents. Third, by combining ...

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    19. High speed spectral domain optical coherence tomography for retinal imaging at 500,000 A‑lines per second

      High speed spectral domain optical coherence tomography for retinal imaging at 500,000 A‑lines per second

      We present a new development of ultrahigh speed spectral domain optical coherence tomography (SDOCT) for human retinal imaging at 850 nm central wavelength by employing two high-speed line scan CMOS cameras, each running at 250 kHz. Through precisely controlling the recording and reading time periods of the two cameras, the SDOCT system realizes an imaging speed at 500,000 A-lines per second, while maintaining both high axial resolution (~8 μm) and acceptable depth ranging (~2.5 mm). With this system, we propose two scanning protocols for human retinal imaging. The first is aimed to achieve isotropic dense sampling and fast ...

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    20. A tomography system for imaging deep tissues

      A tomography system for imaging deep tissues
      An innovative fast optical coherence tomography system obtains high-resolution 3D images of deep retinal tissue structures and their vascularization. The number of people with major eye disease, such as glaucoma, age-related macular degeneration (ARMD), and diabetic retinopathy, is set to increase and to become a major public health problem.1 Several methods are used to diagnose and monitor the progression of such diseases. Optical coherence tomography (OCT) is a noninvasive method for obtaining 3D images of biological tissues. Such images contain information about the microstructures and microvasculature (small vessels and capillaries of the circulatory system) composition of the tissue that ...
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    21. Supercontinuum light source enables in vivooptical microangiography of capillary vessels within tissue beds

      Supercontinuum light source enables in vivooptical microangiography of capillary vessels within tissue beds
      This Letter reports on the use of a supercontinuum light source to achieve ultrahigh resolution and ultrahigh sensitive optical microangiography (OMAG) imaging of microcirculations within tissue beds in vivo. After passing through a specially designed optical filter with a passband of 120 nm centered on 800 nm, the light source is coupled into an optic-fiber-based OMAG system that provides a measured axial resolution of ∼3 μm over a ranging distance of 2 mm. Within this ranging distance, the system gives an averaged signal-to-noise ratio of 87 dB and a sensitivity roll-off of 7 dB at an A-scan rate of 70 ...
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    22. Full range complex spectral domain optical coherence tomography for volumetric imaging at 47 000 A-scans per second

      Full range complex spectral domain optical coherence tomography for volumetric imaging at 47 000 A-scans per second
      In this paper we demonstrate a high speed spectral domain optical coherence tomography (SDOCT) system capable of achieving full range complex imaging at a line scan rate of 47 kHz. By applying a beam-offset method, a constant modulation frequency is introduced into each B-scan that enables reconstruction of the full range complex SDOCT images of in vivo tissue samples. To make use of the full capacity of the detection camera used in the system, system control software is developed that streams the raw spectral fringe data directly into the computer memory. In order to assess performance of the high speed ...
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    23. High-speed 1310 nm-band spectral domain optical coherence tomography at 184,000 lines per second

      High-speed 1310 nm-band spectral domain optical coherence tomography at 184,000 lines per second
      We propose a useful method to boost the imaging speed for spectral domain optical coherence tomography (SDOCT) by multiplying a number of high-speed spectrometers used in the system with selective precise control of data-recording and data-reading phases for spectral cameras employed in each spectrometer. To demonstrate the proposed method, we use two spectrometers built in a 1310 nm-band SDOCT system, each equipped with a high-speed InGaAs line-scan camera capable of 92-kHz line-scan rate, to achieve an unprecedented imaging speed at 184,000 lines/s. We validate the multiplied imaging speed by measuring Doppler-induced phase shift in the spectrograms using a ...
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    24. Multifunctional imaging of human retina and choroid with 1050-nm spectral domain optical coherence tomography at 92-kHz line scan rate

      Multifunctional imaging of human retina and choroid with 1050-nm spectral domain optical coherence tomography at 92-kHz line scan rate
      The light source at ∼1-μm wavelength is attractive for enhanced imaging depth in retinal optical coherence tomography (OCT). In this paper, we report on a 1050-nm spectral domain OCT system, combined with optical microangiography that operates at a 92-kHz line scan rate for multifunctional imaging of the human eye, delivering the volumetric imaging of microstructure and microvasculature within retina and choroid.
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    1. (35 articles) Lin An
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