1. Articles from Mingtao Zhao

    1-17 of 17
    1. Methods and computer program products for quantitative three-dimensional image correction and clinical parameter computation in optical coherence tomography

      Methods and computer program products for quantitative three-dimensional image correction and clinical parameter computation in optical coherence tomography

      Methods and computer program products for quantitative three-dimensional ("3D") image correction in optical coherence tomography. Using the methods and computer program products, index interface (refracting) surfaces from the raw optical coherence tomography ("OCT") dataset from an OCT system can be segmented. Normal vectors or partial derivatives of the curvature at a refracting surface can be calculated to obtain a refracted image voxel. A new position of each desired refracted image voxel can be iteratively computed. New refracted corrected voxel positions to an even sampling grid can be interpolated to provide corrected image data. In some embodiments, clinical outputs from the ...

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      Mentions: Duke University
    2. Sapphire lens-based optical fiber probe for optical coherence tomography

      Sapphire lens-based optical fiber probe for optical coherence tomography

      A probe for an optical coherence tomography system according to an embodiment of the current invention includes a sheath having a proximal end and a distal end and defining a lumen therein, an optical fiber disposed at least partially within the lumen of said sheath, and a sapphire lens attached to the distal end of the sheath to form a fluid-tight seal to prevent fluid from entering the lumen of said sheath. The optical fiber has an end arranged in an optical path with the sapphire lens to provide optical coupling between the sapphire lens and the optical fiber.

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    3. Methods and computer program products for quantitative three-dimensional image correction and clinical parameter computation in optical coherence tomography

      Methods and computer program products for quantitative three-dimensional image correction and clinical parameter computation in optical coherence tomography

      Methods and computer program products for quantitative three-dimensional (“3D”) image correction in optical coherence tomography. Using the methods and computer program products, index interface (refracting) surfaces from the raw optical coherence tomography (“OCT”) dataset from an OCT system can be segmented. Normal vectors or partial derivatives of the curvature at a refracting surface can be calculated to obtain a refracted image voxel. A new position of each desired refracted image voxel can be iteratively computed. New refracted corrected voxel positions to an even sampling grid can be interpolated to provide corrected image data. In some embodiments, clinical outputs from the ...

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      Mentions: Duke University
    4. Sapphire LENS-BASED Optical Fiber Probe For Optical Coherence Tomography

      Sapphire LENS-BASED Optical Fiber Probe For Optical Coherence Tomography

      A probe for an optical coherence tomography system according to an embodiment of the current invention includes a sheath having a proximal end and a distal end and defining a lumen therein, an optical fiber disposed at least partially within the lumen of said sheath, and a sapphire lens attached to the distal end of the sheath to form a fluid-tight seal to prevent fluid from entering the lumen of said sheath. The optical fiber has an end arranged in an optical path with the sapphire lens to provide optical coupling between the sapphire lens and the optical fiber.

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    5. Robot-assisted three-dimensional registration for cochlear implant surgery using a common-path swept-source optical coherence tomography probe

      Robot-assisted three-dimensional registration for cochlear implant surgery using a common-path swept-source optical coherence tomography probe

      Cochlear implantation offers the potential to restore sensitive hearing in patients with severe to profound deafness. However, surgical placement of the electrode array within the cochlea can produce trauma to sensorineural components, particularly if the initial turn of the cochlea is not successfully navigated as the array is advanced. In this work, we present a robot-mounted common-path swept-source optical coherence tomography endoscopic platform for three-dimensional (3-D) optical coherence tomography (OCT) registration and preoperative surgical planning for cochlear implant surgery. The platform is composed of a common-path 600- μ m diameter fiber optic rotary probe attached to a five degrees of freedom ...

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    6. Extravascular Optical Coherence Tomography - Evaluation of Carotid Atherosclerosis and Pravastatin Therapy

      Extravascular Optical Coherence Tomography - Evaluation of Carotid Atherosclerosis and Pravastatin Therapy

      Background and Purpose— Extravascular optical coherence tomography (OCT), as a noninvasive imaging methodology with micrometer resolution, was evaluated in a murine model of carotid atherosclerosis by way of assessing the efficacy of pravastatin therapy. Methods— An OCT device was engineered for extravascular plaque imaging. Wild-type mice and apolipoprotein E–deficient (ApoE −/− ) mice were randomized to 3 treatment groups: (1) wild-type on a diet of standard rodent chow (n=13); (2) ApoE −/− on a high-fat, atherosclerotic diet (HFD; n=13); and (3) ApoE −/− on a HFD given daily pravastatin (n=13). Mice were anesthetized and the left common carotid was surgically ...

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    7. Optical Coherence Tomography System And Method For REAL-TIME Surgical Guidance

      Optical Coherence Tomography System And Method For REAL-TIME Surgical Guidance

      An optical coherence tomography (OCT) system for real-time surgical guidance includes an optical source, an optical fiber configured to be optically coupled to the optical source, a plurality of OCT sensor heads configured to be optically coupled to the optical fiber, an optical detector configured to be optically coupled to the optical fiber, a signal processor configured to communicate with the optical detector to receive detected signals therefrom, and a display system configured to receive OCT image signals from the signal processor and to display an OCT image of at least a portion of a surgical region of interest in ...

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    8. Methods, systems, and computer readable media for synthetic wavelength-based phase unwrapping in optical coherence tomography and spectral domain phase microscopy

      Methods, systems, and computer readable media for synthetic wavelength-based phase unwrapping in optical coherence tomography and spectral domain phase microscopy

      In accordance with this disclosure, methods, systems, and computer readable media for synthetic wavelength-based phase unwrapping in optical coherence tomography are provided. Synthetic wavelength phase unwrapping can be applied to OCT data and can correctly resolve sample motions that are larger than .lamda..sub.o/2. A method for phase unwrapping of an OCT signal can include acquiring raw OCT signal data, interpolating and processing the OCT signal data to obtain a DC spectrum, comparing the raw OCT signal data to the DC spectrum to generate an interference signal, applying Gaussian windows to the interference signal to generate a two ...

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      Mentions: Duke University
    9. Sapphire ball lensed fiber probe for common-path optical coherence tomography in ocular imaging and sensing

      Sapphire ball lensed fiber probe for common-path optical coherence tomography in ocular imaging and sensing

      We describe a novel common-path optical coherence tomography (CP-OCT) fiber probe design using a sapphire ball lens for cross-sectional imaging and sensing in retina vitrectomy surgery. Single mode Gaussian beam (TEM 00 ) simulation was used to optimize lateral resolution and working distance (WD) of the common-path probe. A theoretical sensitivity model for CP-OCT was prosed to assess its optimal performance based an unbalanced photodetector configuration. Two probe designs with working distances (WD) 415μm and 1221μm and lateral resolution 11μm and 18μm, respectively were implemented with sensitivity up to 88dB. The designs are also fully compatible with ...

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    10. Sensing and three-dimensional imaging of cochlea and surrounding temporal bone using swept source high-speed optical coherence tomography

      Sensing and three-dimensional imaging of cochlea and surrounding temporal bone using swept source high-speed optical coherence tomography

      We describe a novel dual-functional optical coherence tomography (OCT) system with both a fiber probe using a sapphire ball lens for cross-sectional imaging and sensing, and a 3-D bulk scanner for 3-D OCT imaging. A theoretical sensitivity model for Common Path (CP)-OCT was proposed to assess its optimal performance based on an unbalanced photodetector configuration. A probe design with working distances (WD) 415μm and lateral resolution 11 μm was implemented with sensitivity up to 88dB. To achieve high-speed data processing and real-time three-dimensional visualization, we use graphics processing unit (GPU) based real-time signal processing and visualization to boost ...

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    11. Sapphire ball lens-based fiber probe for common-path optical coherence tomography and its applications in corneal and retinal imaging

      Sapphire ball lens-based fiber probe for common-path optical coherence tomography and its applications in corneal and retinal imaging

      We describe a common-path swept source optical coherence tomography fiber probe design using a sapphire ball lens for cross-sectional imaging and sensing for retina vitrectomy surgery. The high refractive index ( n = 1.75 ) of the sapphire ball lens improves the focusing power and enables the probe to operate in the intraocular space. The highly precise spherical shape of the sapphire lens also reduces astigmatism and coma compared to fused nonspherical ball lenses. A theoretical sensitivity model for common-path optical coherence tomography (CP-OCT) was developed to assess its optimal performance based on an unbalanced photodetector configuration. Two probe designs—with working ...

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    12. Corneal biometry from volumetric SDOCT and comparison with existing clinical modalities

      Corneal biometry from volumetric SDOCT and comparison with existing clinical modalities

      We present a comparison of corneal biometric values from dense volumetric spectral domain optical coherence tomography (SDOCT) scans to reference values in both phantoms and clinical subjects. We also present a new optically based “keratometric equivalent power” formula for SDOCT that eliminates previously described discrepancies between corneal power form SDOCT and existing clinical modalities. Phantom objects of varying radii of curvature and corneas of normal subjects were imaged with a clinical SDOCT system. The optically corrected three-dimensional surfaces were used to recover radii of curvature and power as appropriate. These were then compared to the manufacturer’s reference values in ...

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      Mentions: Duke University
    13. Methods And Computer Program Products For Quantitative Three-Dimensional Image Correction And Clinical Parameter Computation In Optical Coherence Tomography

      Methods And Computer Program Products For Quantitative Three-Dimensional Image Correction And Clinical Parameter Computation In Optical Coherence Tomography

      Methods and computer program products for quantitative three- dimensional ("3D") image correction in optical coherence tomography. Using the methods and computer program products, index interface (refracting) surfaces from the raw optical coherence tomography ("OCT") dataset from an OCT system can be segmented. Normal vectors or partial derivatives of the curvature at a refracting surface can be calculated to obtain a refracted image voxel. A new position of each desired refracted image voxel can be iteratively computed. New refracted corrected voxel positions to an even sampling grid can be interpolated to provide corrected image data. In some embodiments, clinical outputs from ...

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      Mentions: Duke University
    14. 3D refraction correction and extraction of clinical parameters from spectral domain optical coherence tomography of the cornea

      3D refraction correction and extraction of clinical parameters from spectral domain optical coherence tomography of the cornea

      Capable of three-dimensional imaging of the cornea with micrometer-scale resolution, spectral domain-optical coherence tomography (SDOCT) offers potential advantages over Placido ring and Scheimpflug photography based systems for accurate extraction of quantitative keratometric parameters. In this work, an SDOCT scanning protocol and motion correction algorithm were implemented to minimize the effects of patient motion during data acquisition. Procedures are described for correction of image data artifacts resulting from 3D refraction of SDOCT light in the cornea and from non-idealities of the scanning system geometry performed as a pre-requisite for accurate parameter extraction. Zernike polynomial 3D reconstruction and a recursive half searching ...

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      Mentions: Duke University
    15. Synthetic wavelength based phase unwrapping in spectral domain optical coherence tomography

      Synthetic wavelength based phase unwrapping in spectral domain optical coherence tomography
      Phase sensing implementations of spectral domain optical coherence tomography (SDOCT) have demonstrated the ability to measure nanometer-scale temporal and spatial profiles of samples. However, the phase information suffers from a 2π ambiguity that limits observations of larger sample displacements to lengths less than half the source center wavelength. We introduce a synthetic wavelength phase unwrapping technique in SDOCT that uses spectral windowing and corrects the 2π ambiguity, providing accurate easurements of sample motion with information gained from standard SDOCT processing. We demonstrate this technique by using a common path implementation of SDOCT and correctly measure phase profiles from a phantom ...
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      Mentions: Duke University
    16. Synthetic wavelength-based phase unwrapping in Fourier domain optical coherence tomography

      Phase-sensitive adjuncts to optical coherence tomography (OCT) including Doppler and polarization-sensitive implementations allow for quantitative depth-resolved measurements of sample structure and dynamics including fluid flows and orientation of birefringent structures. The development of Fourier-domain OCT (FDOCT), particularly spectrometer-based spectral-domain systems with no moving parts (spectral-domain OCT or SDOCT), have greatly enhanced the phase stability of OCT systems particularly when implemented in a common-path geometry. The latter combination has given rise to a new class of nm-scale sensitive quantitative phase microscopies we have termed spectral domain phase microscopy. However, the phase information in all of these techniques suffers from a 2 ...
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      Mentions: Duke University
    17. Single-camera sequential-scan-based polarization-sensitive SDOCT for retinal imaging

      Single-camera sequential-scan-based polarization-sensitive SDOCT for retinal imaging
      A single-camera, high-speed, polarization-sensitive, spectral-domain optical-coherence-tomography system was developed to measure the polarization properties of the in vivo human retina. A novel phase-unwrapping method in birefringent media is described to extract the total reflectivity, accumulative retardance, and fast-axis orientation from a specially designed sequence of polarization states incident on the sample. A quarter-wave plate was employed to test the performance of the system. The average error and standard deviation of retardation measurements were 3.2° and 2.3°, respectively, and of the fast-axis orientation 1.2° and 0.7° over the range of 0°-180°. The depolarization properties of the ...
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      Mentions: Duke University
    1-17 of 17
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    1. (9 articles) Duke University
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    Single-camera sequential-scan-based polarization-sensitive SDOCT for retinal imaging Synthetic wavelength based phase unwrapping in spectral domain optical coherence tomography 3D refraction correction and extraction of clinical parameters from spectral domain optical coherence tomography of the cornea Methods And Computer Program Products For Quantitative Three-Dimensional Image Correction And Clinical Parameter Computation In Optical Coherence Tomography Corneal biometry from volumetric SDOCT and comparison with existing clinical modalities Sapphire ball lens-based fiber probe for common-path optical coherence tomography and its applications in corneal and retinal imaging Sapphire ball lensed fiber probe for common-path optical coherence tomography in ocular imaging and sensing Extravascular Optical Coherence Tomography - Evaluation of Carotid Atherosclerosis and Pravastatin Therapy Sapphire lens-based optical fiber probe for optical coherence tomography The Structural and Comparative Analysis of Intravitreal Dexamethasone Implant (Ozurdex) and Anti-VEGF Injection in Branched Retinal Vein Occlusion Patients by Optical Coherence Tomography Angiography Images Quantitation Vascular Responses to First-Generation Sirolimus-Eluting Stents and Bare-Metal Stents Beyond 10 Years Ocular Parameters Evaluation in Relation to the Refractive Error using Optical Coherence Topography