1. Articles from Lian Duan

    1-20 of 20
    1. Optical coherence tomography apparatus for selectively visualizing and analyzing vascular network of choroidal layer, and image-processing program and image-processing method for the same

      Optical coherence tomography apparatus for selectively visualizing and analyzing vascular network of choroidal layer, and image-processing program and image-processing method for the same

      From OCT-measured data, only the image data of the choroidal vascular network present in the layer of the choroidal layer is selectively extracted, thereby accurately obtaining the thickness of the choroidal vessels and thickness of the choroidal vascular network from the image data, to allow for quantitative evaluation of the choroidal vascular network. The optical coherence tomography apparatus has an optical coherence tomography device, and a computer that processes the three-dimensional OCT tomographic images obtained based on the OCT-measured data acquired by the optical coherence tomography device. The computer functions as a means for selectively separating out only the images ...

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    2. Spectroscopic Doppler analysis for visible-light optical coherence tomography

      Spectroscopic Doppler analysis for visible-light optical coherence tomography

      Retinal oxygen metabolic rate can be effectively measured by visible-light optical coherence tomography (vis-OCT), which simultaneously quantifies oxygen saturation and blood flow rate in retinal vessels through spectroscopic analysis and Doppler measurement, respectively. Doppler OCT relates phase variation between sequential A-lines to the axial flow velocity of the scattering medium. The detectable phase shift is between − π −π and π π due to its periodicity, which limits the maximum measurable unambiguous velocity without phase unwrapping. Using shorter wavelengths, vis-OCT is more vulnerable to phase ambiguity since flow induced phase variation is linearly related to the center wavenumber of the probing light. We eliminated the ...

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    3. Colposcopic imaging using visible-light optical coherence tomography

      Colposcopic imaging using visible-light optical coherence tomography

      High-resolution colposcopic optical coherence tomography (OCT) provides key anatomical measures, such as thickness and minor traumatic injury of vaginal epithelium, of the female reproductive tract noninvasively. This information can be helpful in both fundamental investigations in animal models and disease screenings in humans. We present a fiber-based visible-light OCT and two probe designs for colposcopic application. One probe conducts circular scanning using a DC motor, and the other probe is capable of three-dimensional imaging over a 4.6 × 4.6 - mm 2 4.6×4.6-mm2 area using a pair of galvo scanners. Using this colposcopic vis-OCT with both probes ...

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    4. Program for correcting data measured by PS-OCT and PS-OCT system equipped with the program

      Program for correcting data measured by PS-OCT and PS-OCT system equipped with the program

      Data measured by PS-OCT is corrected in a non-linear manner to enhance the quantitative analysis capability of PS-OCT and permit accurate quantitative diagnosis, including diagnosis of disease stage of lesions, as a useful means for computer diagnosis. Even when retardation per PS-OCT 1 contains error and becomes noise and its distribution is not normal or symmetrical around the true value, measured data is converted using a distribution conversion function obtained by analyzing the characteristics of noise via Monte Carlo simulation to remove the systematic error and estimate the true value otherwise buried in noise and thereby correct the PS-OCT 1 ...

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    5. Classification of basal cell carcinoma in human skin using machine learning and quantitative features captured by polarization sensitive optical coherence tomography

      Classification of basal cell carcinoma in human skin using machine learning and quantitative features captured by polarization sensitive optical coherence tomography

      We report the first fully automated detection of basal cell carcinoma (BCC), the most commonly occurring type of skin cancer, in human skin using polarization-sensitive optical coherence tomography (PS-OCT). Our proposed automated procedure entails building a machine-learning based classifier by extracting image features from the two complementary image contrasts offered by PS-OCT, intensity and phase retardation (PR), and selecting a subset of features that yields a classifier with the highest accuracy. Our classifier achieved 95.4% sensitivity and specificity, validated by leave-one-patient-out cross validation (LOPOCV), in detecting BCC in human skin samples collected from 42 patients. Moreover, we show the ...

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    6. Iterative re-weighted approach to high-resolution optical coherence tomography with narrow-band sources

      Iterative re-weighted approach to high-resolution optical coherence tomography with narrow-band sources

      Optical coherence tomography (OCT) is a non-invasive optical imaging modality capable of high resolution imaging of internal tissue structures. It is widely believed that the high axial resolution in OCT systems requires a wide-bandwidth light source. As a result, often the potential advantages of narrow-bandwidth sources (in terms of cost and/or imaging speed) are understood to come at the cost of significant reduction in imaging resolution. In this paper, we argue that this trade-off between resolution and speed is a shortcoming imposed by the-state-of-the-art A-scan reconstruction algorithm, Fast Fourier Transform, and can be circumvented through use of alternative processing ...

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    7. Polarization-sensitive interleaved optical coherence tomography

      Polarization-sensitive interleaved optical coherence tomography

      We introduce a new strategy for single-mode fiber based polarization-sensitive (PS-) optical coherence tomography (OCT) using orthogonally polarized optical frequency combs (OFC) in the sample arm. The two OFCs are tuned to be interleaved in the spectral domain, permitting simultaneous measurement of both polarization states from the same spatial region C close to the location of zero pathlength delay. The two polarization states of the beam in the sample arm are demultiplexed by interpolation after performing wavelength stabilization via a two-mirror calibration method. The system uses Jones matrix methods to measure quantitatively the round-trip phase retardation B-scans in the sample ...

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    8. Single-shot speckle noise reduction by interleaved optical coherence tomography

      Single-shot speckle noise reduction by interleaved optical coherence tomography

      Speckle noise is one of the dominant factors that degrade image quality in optical coherence tomography (OCT). Here, we propose a new strategy, interleaved OCT (iOCT), for spatial compounding and angular compounding. We demonstrate the efficiency of compounding with iOCT to restrain speckle noise without compromising imaging speed in phantoms and tissue samples.

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    9. Optical Coherence Tomography Apparatus For Selectively Visualizing And Analyzing Choroid Vascular Plexus, And IMAGE-PROCESSING Program And IMAGE-PROCESSING Method Therefor

      Optical Coherence Tomography Apparatus For Selectively Visualizing And Analyzing Choroid Vascular Plexus, And IMAGE-PROCESSING Program And IMAGE-PROCESSING Method Therefor

      From OCT measurement data, image data for only the choroid vascular plexus present in the choroid layer is selectively extracted and the size of the choroid blood vessels and thickness of the choroid vascular plexus are obtained accurately from the image data, making quantitative evaluation of the choroid vascular plexus possible. The optical coherence tomography apparatus is provided with an optical coherence tomograph and a computer for performing image-processing on the three-dimensional OCT tomographic image obtained on the basis of the OCT measurement data acquired by the optical coherence tomogrph. The computer functions as a means for selectively isolating only ...

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    10. Automated identification of basal cell carcinoma by polarization-sensitive optical coherence tomography

      Automated identification of basal cell carcinoma by polarization-sensitive optical coherence tomography

      We report an automated classifier to detect the presence of basal cell carcinoma in images of mouse skin tissue samples acquired by polarization-sensitive optical coherence tomography (PS-OCT). The sensitivity and specificity of the classifier based on combined information of the scattering intensity and birefringence properties of the samples are significantly higher than when intensity or birefringence information are used alone. The combined information offers a sensitivity of 94.4% and specificity of 92.5%, compared to 78.2% and 82.2% for intensity-only information and 85.5% and 87.9% for birefringence-only information. These results demonstrate that analysis of the ...

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    11. Quantitative measurements of strain and birefringence with common-path polarization-sensitive optical coherence tomography

      Quantitative measurements of strain and birefringence with common-path polarization-sensitive optical coherence tomography

      We demonstrate the first system for optical coherence tomography (OCT) that enables simultaneous measurement of quantitative birefringence and strain in biological samples using a common-path configuration. Owing to its superior phase stability, common-path polarization sensitive optical coherence tomography (CoPPSe-OCT) achieves a sub-nanometer displacement sensitivity of 0.52 nm at an SNR of 48 dB. We utilize CoPPSe-OCT to measure reflectance, birefringence, and strain for distinguishing burnt regions in a birefringent biological sample (chicken breast muscle).

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    12. Scalable multiplexing for parallel imaging with interleaved optical coherence tomography

      Scalable multiplexing for parallel imaging with interleaved optical coherence tomography

      We demonstrate highly parallel imaging with interleaved optical coherence tomography (iOCT) using an in-house-fabricated, air-spaced virtually-imaged phased array (VIPA). The air-spaced VIPA performs spectral encoding of the interferograms from multiple lateral points within a single sweep of the source and allows us to tune and balance several imaging parameters: number of multiplexed points, ranging depth, and sensitivity. In addition to a thorough discussion of the parameters and operating principles of the VIPA, we experimentally demonstrate the effect of different VIPA designs on the multiplexing potential of iOCT. Using a 200-kHz light source, we achieve an effective A-scan rate of 3 ...

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    13. Advanced multi-contrast Jones matrix optical coherence tomography for Doppler and polarization sensitive imaging

      Advanced multi-contrast Jones matrix optical coherence tomography for Doppler and polarization sensitive imaging

      An advanced version of Jones matrix optical coherence tomography (JMT) is demonstrated for Doppler and polarization sensitive imaging of the posterior eye. JMT is capable of providing localized flow tomography by Doppler detection and investigating the birefringence property of tissue through a three-dimensional (3-D) Jones matrix measurement. Owing to an incident polarization multiplexing scheme based on passive optical components, this system is stable, safe in a clinical environment, and cost effective. Since the properties of this version of JMT provide intrinsic compensation for system imperfection, the system is easy to calibrate. Compared with the previous version of JMT, this advanced ...

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    14. Automated segmentation and characterization of choroidal vessels in high-penetration optical coherence tomography

      Automated segmentation and characterization of choroidal vessels in high-penetration optical coherence tomography

      An automated choroidal vessel segmentation and quantification method for high-penetration optical coherence tomography (OCT) was developed for advanced visualization and evaluation of the choroidal vasculature. This method uses scattering OCT volumes for the segmentation of choroidal vessels by using a multi-scale adaptive threshold. The segmented choroidal vessels are then processed by multi-scale morphological analysis to quantify the vessel diameters. The three-dimensional structure and the diameter distribution of the choroidal vasculature were then obtained. The usefulness of the method was then evaluated by analyzing the OCT volumes of normal subjects.

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    15. Optical Rheology of Porcine Sclera by Birefringence Imaging

      Optical Rheology of Porcine Sclera by Birefringence Imaging

      Purpose To investigate a relationship between birefringence and elasticity of porcine sclera ex vivo using polarization-sensitive optical coherence tomography (PS-OCT). Methods Elastic parameters and birefringence of 19 porcine eyes were measured. Four pieces of scleral strips which were parallel to the limbus, with a width of 4 mm, were dissected from the optic nerve head to the temporal side of each porcine eye. Birefringence of the sclera was measured with a prototype PS-OCT. The strain and force were measured with a uniaxial material tester as the sample was stretched with a speed of 1.8 mm/min after preconditioning. A ...

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    16. Passive component based multifunctional Jones matrix swept source optical coherence tomography for Doppler and polarization imaging

      Passive component based multifunctional Jones matrix swept source optical coherence tomography for Doppler and polarization imaging

      We present a fiber based multifunctional Jones matrix swept source optical coherence tomography (SS-OCT) system for Doppler and polarization imaging. Jones matrix measurement without using active components such as electro-optic modulators is realized by incident polarization multiplexing based on independent delay of two orthogonal polarization states and polarization diversity detection. In addition to polarization sensitivity, this system measures Doppler flow without extra hardware for phase stabilized SS-OCT detection. An eighth-wave plate was measured to demonstrate the polarization detection accuracy. The optic nerve head of a retina was measured in vivo. Detailed vasculature and birefringent structures were investigated simultaneously.

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    17. Automated detection of chorio-scleral interface using polarization-sensitive optical coherence tomography

      Automated detection of chorio-scleral interface using polarization-sensitive optical coherence tomography

      A polarization sensitive optical coherence tomography based automated algorithm for segmentation of the chorio-scleral interface is presented. The algorithm employs a two-step segmentation approach. At first, local birefringence based segmentation with low precision is performed to roughly distinguish the choroid and sclera. Successively, a depth oriented slope fitting to phase retardation is applied in both the choroid and sclera. The interface is determined as the cross-point of the two phase retardation slope lines. The algorithm shows potential for functional, objective, and volumetric choroid thickness measurement

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    18. Automated phase retardation oriented segmentation of chorio-scleral interface by polarization sensitive optical coherence tomography

      Automated phase retardation oriented segmentation of chorio-scleral interface by polarization sensitive optical coherence tomography

      An automated chorio-scleral interface (CSI) detection algorithm based on polarization sensitive optical coherence tomography (PS-OCT) is presented. This algorithm employs a two-step scheme based on the phase retardation variation detected by PS-OCT. In the first step, a rough CSI segmentation is implemented to distinguish the choroid and sclera by using depth-oriented second derivative of the phase retardation. Second, the CSI is further finely defined as the intersection of lines fitted to the phase retardation in the choroid and sclera. This algorithm challenges the current back-scattering intensity based CSI segmentation approaches that are not fully based on anatomical and morphological evidence ...

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    19. Monte-Carlo-based phase retardation estimator for polarization sensitive optical coherence tomography

      Monte-Carlo-based phase retardation estimator for polarization sensitive optical coherence tomography
      A Monte-Carlo-based phase retardation estimator is developed to correct the systematic error in phase retardation measurement by polarization sensitive optical coherence tomography (PS-OCT). Recent research has revealed that the phase retardation measured by PS-OCT has a distribution that is neither symmetric nor centered at the true value. Hence, a standard mean estimator gives us erroneous estimations of phase retardation, and it degrades the performance of PS-OCT for quantitative assessment. In this paper, the noise property in phase retardation is investigated in detail by Monte-Carlo simulation and experiments. A distribution transform function is designed to eliminate the systematic error by using ...
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    20. A novel spectral calibration method in spectral domain optical coherence tomography

      novel but brief method is developed for spectral domain optical coherence tomography(SD-OCT). This method is based on two mirror locales in both sample arm and reference arm, independent of a mercury argon calibration source, and then get the exact spectral distribution on the line array charge coupled device (CCD) through fitting and interpolation. The rescaling parameters is determined by a short time Fourier transformation(STFT) and a series of calculation. A SD-OCT system is set up. The signal-noise-ratio(SNR) of this system is experimentally found to be 51dB. Axial resolution is 8.5µm. Improved 3D image of human retain ...
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    1-20 of 20
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    Monte-Carlo-based phase retardation estimator for polarization sensitive optical coherence tomography Automated detection of chorio-scleral interface using polarization-sensitive optical coherence tomography Passive component based multifunctional Jones matrix swept source optical coherence tomography for Doppler and polarization imaging Optical Rheology of Porcine Sclera by Birefringence Imaging Automated phase retardation oriented segmentation of chorio-scleral interface by polarization sensitive optical coherence tomography Automated segmentation and characterization of choroidal vessels in high-penetration optical coherence tomography Advanced multi-contrast Jones matrix optical coherence tomography for Doppler and polarization sensitive imaging Automated identification of basal cell carcinoma by polarization-sensitive optical coherence tomography Iterative re-weighted approach to high-resolution optical coherence tomography with narrow-band sources 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