1. Articles from Yi Wang

    1-25 of 25
    1. Fast Retinal Segmentation Based on the Wave Algorithm

      Fast Retinal Segmentation Based on the Wave Algorithm

      The retinal layer segmentation technique of optical coherence tomography (OCT) data is essential for the diagnosis of ophthalmic and systemic diseases. To achieve fast and accurate retinal layer segmentation, a new medical image segmentation method (wave algorithm) is proposed based on the mathematical model of the fluid potential energy equation in fluid mechanics. A change in the gray value in the image is converted into a change in the potential energy in the ideal fluid (wave), thereby transforming the image segmentation problem into a problem that solves the potential energy based on the fluid potential energy equation. In the process ...

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    2. Simultaneous detection of cerebral blood perfusion and cerebral edema using swept‐source optical coherence tomography

      Simultaneous detection of cerebral blood perfusion and cerebral edema using swept‐source optical coherence tomography

      The progression of ischemic cerebral edema (CE) is closely related to the level of cerebral blood perfusion (CBP) and affects each other. Simultaneous detection of CBP and CE is helpful in understanding the mechanisms of ischemic cerebral edema development. In this article, a wide field of view (FOV) SS‐OCT system was used to detect CE status and CBP levels simultaneously in middle cerebral artery occlusion (MCAO) rats. Images reflecting these two physiological states can be reconstructed with only one C‐scan. We quantify these two physiological states into 4 parameters, which contain two vascular parameters (vascular displacement distance and ...

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    3. Primary Acute Angle-Closure Glaucoma: Three-Dimensional Reconstruction Imaging of Optic Nerve Heard Structure in Based on Optical Coherence Tomography (OCT)

      Primary Acute Angle-Closure Glaucoma: Three-Dimensional Reconstruction Imaging of Optic Nerve Heard Structure in Based on Optical Coherence Tomography (OCT)

      BACKGROUND : In glaucoma, the cup to plate ratio enlargement is a recognized pathological phenomenon. At present, the research on optic nerve in China and abroad mainly focuses on 2-dimensional research, and the measurement of 3-dimensional volume data is less well studied. Therefore, the recognition of 3-dimensional morphological changes is conducive to timely clinical intervention to prevent or slow down progressive vision loss. MATERIAL AND METHODS : In this paper, optical coherence tomography (OCT) volume imaging technology was used to analyze and compare the morphological changes of primary acute angle-closure glaucoma in three-dimensional morphology, reconstruct the volume data of three-dimensional optic nerve ...

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      Mentions: Yi Wang
    4. Spectral domain optical coherence tomography with sub-micrometer sensitivity for measurement of central corneal thickness

      Spectral domain optical coherence tomography with sub-micrometer sensitivity for measurement of central corneal thickness

      We demonstrated a method for measurement of central corneal thickness (CCT) with a sub-micrometer sensitivity using a spectral domain optical coherence tomography system without needing a super broad bandwidth light source. By combining the frequency and phase components of Fourier transform, the method is capable of measurement of a large dynamic range with a high sensitivity. Absolute phases are retrieved by comparing the correlations between the detected and simulated interference fringes. The phase unwrapping ability of the present method was quantitatively tested by measuring the displacement of a piezo linear stage. The human CCTs of six volunteers were measured to ...

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      Mentions: Yi Wang
    5. Quantification of cerebral vascular perfusion density via optical coherence tomography based on locally adaptive regional growth

      Quantification of cerebral vascular perfusion density via optical coherence tomography based on locally adaptive regional growth

      Optical coherence tomography (OCT) angiography is a noninvasive imaging modality that produces volumetric views of blood flow perfusion in vivo with resolution at capillary level, which has been widely adopted to monitor cerebral perfusion status after stroke in experimental settings. Accurate quantification of cerebral perfusion from OCT angiograms is important for understanding the cerebral vascular pathophysiology and assessing the treatment of ischemic stroke. Quantification of blood vessels from OCT angiography faces some problems; one is uneven backscatter (which causes some blood vessels to be very bright, some very dark), and the other is that the brightness in the same blood ...

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      Mentions: Yi Wang
    6. Assessment of microvasculature flow state with a high speed all-optic dual-modal system of optical coherence tomography and photoacoustic imaging

      Assessment of microvasculature flow state with a high speed all-optic dual-modal system of optical coherence tomography and photoacoustic imaging

      We propose a high speed all-optic dual-modal system that combines spectral domain optical coherence tomography (SDOCT) and photoacoustic imaging (PAI) to evaluate microvasculature flow states. A homodyne interferometer was used to remotely detect the surface vibration caused by photoacoustic (PA) waves. The PA excitation, PA probing and SDOCT probing beams share the same X-Y galvanometer scanner to perform fast two-dimensional scanning. In addition, we introduced multi-excitation, dual-channel acquisition and sensitivity compensation to improve the imaging speed of the PAI sub-system. The total time for imaging a sample with 256 × 256 pixels is less than 1 minute. The performance of the ...

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      Mentions: Yi Wang
    7. Assessment of macular function in patients with idiopathic Epiretinal membrane by multifocal Electroretinography: correlation with visual acuity and optical coherence tomography

      Assessment of macular function in patients with idiopathic Epiretinal membrane by multifocal Electroretinography: correlation with visual acuity and optical coherence tomography

      Background This study evaluates the macular function changes in patients with idiopathic macular epiretinal membrane (ERM) by multifocal electroretinography (mfERG) and their correlations with visual acuity and central macular thickness (CMT) by optical coherence tomography (OCT). Methods Twenty eyes of 20 patients with ERM underwent OCT and mfERG examinations. The response amplitude densities and implicit times of mfERG were compared to the control fellow eyes. Correlation analyses among visual acuity, central macular thickness and mfERG values in the central two concentric rings were performed. Results The mfERG P1 response amplitude densities in ring 1–2 and P1 implicit time in ...

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    8. Pathophysiological correlations between fundus fluorescein angiography and optical coherence tomography results in patients with idiopathic epiretinal membranes

      Pathophysiological correlations between fundus fluorescein angiography and optical coherence tomography results in patients with idiopathic epiretinal membranes

      The aim of the current study was to determine the association between fundus fluorescein angiography (FFA) image results, optical coherence tomography (OCT) imaging results and visual functions in patients with idiopathic epiretinal membranes (ERMs). A total of 80 eyes from 40 patients diagnosed with ERM were analyzed. Best‑corrected visual acuity (BCVA) and metamorphopsia were measured using the Early Treatment Diabetic Retinopathy Study eye chart and M‑charts, respectively. Macular thickness and volume were determined using OCT. Macular vascular leakage and distortion, and foveal avascular zone (FAZ) diameters were assessed using FFA. BCVA and M‑chart results confirmed macular degeneration ...

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    9. Optical coherence tomography with pre-calculated reference spectra

      Optical coherence tomography with pre-calculated reference spectra

      The resample of spectra which is essential for high-precision spectral-domain OCT data processing is sophisticated, and its precision is dependent on the method and equipment. In this paper, we proposed an OCT without inverse FFT. A series of reference spectra corresponding to different optical path length difference was used to convolve with spectra gotten by OCT to acquire time-domain tomography instead of inverse FFT, thus eliminating the resample of spectra. The reference spectra were calculated before imaging and corrected with correction spectrum from sample arm to compensate the influence of sample arm. Experiment was done with a mirror as sample ...

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    10. Hemodynamic changes in a rat parietal cortex after endothelin-1-induced middle cerebral artery occlusion monitored by optical coherence tomography

      Hemodynamic changes in a rat parietal cortex after endothelin-1-induced middle cerebral artery occlusion monitored by optical coherence tomography

      A blockage of the middle cerebral artery (MCA) on the cortical branch will seriously affect the blood supply of the cerebral cortex. Real-time monitoring of MCA hemodynamic parameters is critical for therapy and rehabilitation. Optical coherence tomography (OCT) is a powerful imaging modality that can produce not only structural images but also functional information on the tissue. We use OCT to detect hemodynamic changes after MCA branch occlusion. We injected a selected dose of endothelin-1 (ET-1) at a depth of 1 mm near the MCA and let the blood vessels follow a process first of occlusion and then of slow ...

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    11. Measurement of cerebral blood flow rate and its relationship with brain function using optical coherence tomography

      Measurement of cerebral blood flow rate and its relationship with brain function using optical coherence tomography

      Activity of brain neurons will lead to changes in local blood flow rate (BFR). Thus, it is important to measure the local BFR of cerebral cortex on research of neuron activity in vivo, such as rehabilitation evaluation after stroke, etc. Currently, laser Doppler flowmetry is commonly used for blood flow measurement, however, relatively low resolution limits its application. Optical coherence tomography (OCT) is a powerful noninvasive 3D imaging modality with high temporal and spatial resolutions. Furthermore, OCT can provide flow distribution image by calculating Doppler frequency shift which makes it possible for blood flow rate measurement. In this paper, we ...

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    12. Blood flow changes after unilateral carotid artery ligation monitored by optical coherence tomography

      Blood flow changes after unilateral carotid artery ligation monitored by optical coherence tomography

      Unilateral carotid artery ligation which could induce adaptive improvement is a classic model that has been widely used to study pathology of ischemic disease. In those studies, blood flow is an important parameter to characterize the ischemia. Optical coherence tomography (OCT) is a powerful imaging modality which can provide depth resolved images in biological tissue with high spatial and temporal resolution. SPF rats was anesthetized with isoflurane and divided into two groups. In first group, bilateral carotid artery was surgically exposed, and then left carotid artery was ligated. Blood flow changes of the contralateral carotid artery was monitored using high ...

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    13. Measurement of strain and strain rate in embryonic chick heart using spectral domain optical coherence tomography

      Measurement of strain and strain rate in embryonic chick heart using spectral domain optical coherence tomography

      It is important to measure embryonic heart myocardial wall strain and strain rate for understanding the mechanisms of embryonic heart development. Optical coherence tomography (OCT) can provide depth resolved images with high spatial and temporal resolution, which makes it have the potential to reveal the complex myocardial activity in the early stage embryonic heart. We develop a novel method to measure strain in embryonic chick heart based on spectral domain OCT images and subsequent image processing. We perform 4D(x,y,z,t) scanning on the outflow tract (OFT) of chick embryonic hearts in HH18 stage (~3 days of incubation ...

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    14. In vivo assessment of wall strain in embryonic chick heart by spectral domain optical coherence tomography

      In vivo assessment of wall strain in embryonic chick heart by spectral domain optical coherence tomography

      The ability to measure in vivo wall strain in embryonic hearts is important for fully understanding the mechanisms of cardiac development. Optical coherence tomography (OCT) is a powerful tool for the three-dimensional imaging of complex myocardial activities in early-stage embryonic hearts with high spatial and temporal resolutions. We describe a method to analyze periodic deformations of myocardial walls and evaluate in vivo myocardial wall strains with a high-speed spectral domain OCT system. We perform four-dimensional scanning on the outflow tract (OFT) of chick embryonic hearts and determine a special cross-section in which the OFT can be approximated as an annulus ...

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    15. All-optically integrated photo-acoustic microscopy and optical coherence tomography based on a single Michelson detector

      All-optically integrated photo-acoustic microscopy and optical coherence tomography based on a single Michelson detector

      An all-optically noncontact dual-mode imaging system using a single Michelson detector that simultaneously achieved photo-acoustic microscopy (PAM) and optical coherence tomography (OCT) is presented. The pulse laser-induced photo-acoustic signals and the back-scattered photons were alternately detected by a single Michelson detector. The spatial resolution and imaging capability of the dual-mode imaging system were testified by scattering phantoms. Furthermore, in vivo images of the mouse ear demonstrated that the PAM-OCT can provide complementary anatomical and functional information for imaging of biological tissues, which could be the best co-imaging strategy of PAM and OCT in biomedicine

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      Mentions: Yi Wang UC Irvine
    16. Measurement of wall shear stress in chick embryonic heart using optical coherence tomography

      Measurement of wall shear stress in chick embryonic heart using optical coherence tomography

      The cardiac development is a complicated process affected by genetic and environmental factors. Wall shear stress (WSS) is one of the components which have been proved to influence the morphogenesis during early stages of cardiac development. To study the mechanism, WSS measurement is a step with significant importance. WSS is caused by blood flow imposed on the inner surface of the heart wall and it can be determined by calculating velocity gradients of blood flow in a direction perpendicular to the wall. However, the WSS of the early stage embryonic heart is difficult to measure since the embryonic heart is ...

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      Mentions: Yi Wang
    17. Approach to quantify two-dimensional strain of chick embryonic heart in early stage based on spectral domain optical coherence tomography

      Approach to quantify two-dimensional strain of chick embryonic heart in early stage based on spectral domain optical coherence tomography

      The heart undergoes remarkable changes during embryonic development due to genetic programming and epigenetic influences, in which mechanical loads is a key factor. As embryonic research development, an important goal is to develop mathematical models that describe the influence of mechanics on embryonic heart development. However, basic parameters for the modeling are difficult to acquire since the embryonic heart is tiny and beating fast in the early stages. Optical coherence tomography (OCT) technique provides depth-resolved image with high resolution and high acquisition speed in a noninvasive manner. In this paper, we performed 4D[(x,y,z) + t] scan on the ...

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      Mentions: Yi Wang
    18. Practical approach for dispersion compensation in spectral-domain optical coherence tomography

      Practical approach for dispersion compensation in spectral-domain optical coherence tomography

      e proposed and demonstrated a digital method of dispersion compensation suitable for spectral-domain optical coherence tomography. The wavelength coordinate of the coherence spectrum was calibrated digitally using a two-order polynomial. A software-based scheme was introduced to determine the polynomial coefficients of the polynomial fitting spectrum wavelength. Therefore, the spectrum deformation introduced by dispersion can be compensated effectively. This method was experimentally validated by in vivo imaging an early-stage chick embryonic heart.

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      Mentions: Yi Wang
    19. Resolution Improvement with Two-Dimensional Digital Focusing Method in Optical Coherence Tomography

      Resolution Improvement with Two-Dimensional Digital Focusing Method in Optical Coherence Tomography

      This paper presents a two-dimensional (2D) digital focusing method to alleviate the compromise between the resolution and depth of field (DOF) in spectral domain optical coherence tomography (SDOCT). A scalar diffraction model is developed to simulate the wave propagation process from out-of-focus scatterers and the inverse scattering problem is solved. The wavenumber domain algorithm is applied to improve the transverse resolution, and the matched filter to improve the axial resolution. Image reconstruction with spatially invariant resolution can be achieved. The 2D imaging experimental results of fresh pig liver prove the effectiveness of the proposed method.

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      Mentions: Yi Wang
    20. Noncontact photoacoustic imaging achieved by using a low-coherence interferometer as the acoustic detector

      Noncontact photoacoustic imaging achieved by using a low-coherence interferometer as the acoustic detector

      We report on a noncontact photoacoustic imaging (PAI) technique in which a low-coherence interferometer [(LCI), optical coherence tomography (OCT) hardware] is utilized as the acoustic detector. A synchronization approach is used to lock the LCI system at its highly sensitive region for photoacoustic detection. The technique is experimentally verified by the imaging of a scattering phantom embedded with hairs and the blood vessels within a mouse ear in vitro. The system’s axial and lateral resolutions are evaluated at 60 and 30 μm, respectively. The experimental results indicate that PAI in a noncontact detection mode is possible with high resolution ...

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    21. Measurement of particle concentration in flow by statistical analyses of optical coherence tomography signals

      Measurement of particle concentration in flow by statistical analyses of optical coherence tomography signals

      We present a statistic method to measure the concentration of particles in flow by the use of optical coherence tomography (OCT). This method is based on the fact that the fluctuating numbers of particles contained within a small OCT detection volume caused by Brownian motion are governed by Poissonian distribution. Particle concentration is evaluated from the statistical analyzes of the OCT intensity signals that are backscattered by the moving particles. The method is experimentally verified with flow phantoms of polymer microspheres. Experimental results are in good agreement with the theoretical ones for low concentrations while relatively large discrepancies emerge for ...

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    22. Autocorrelation optical coherence tomography for mapping transverse particle-flow velocity

      Autocorrelation optical coherence tomography for mapping transverse particle-flow velocity

      We present an autocorrelation method to quantitatively map transverse particle-flow velocity with a Fourier-domain optical coherence tomography system. This method is derived from the intensity fluctuation of the backscattered light modulated by flowing particles. When passing through the probe beam, moving particles encode a transit time into the backscattered light. The slope of the normalized autocorrelation function of the backscattered light is proportional to the transverse velocity. The proposed method is experimentally verified using an intralipid scattering flow phantom.

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    23. High-resolution computed tomography of refractive index distribution by transillumination low-coherence interferometry

      High-resolution computed tomography of refractive index distribution by transillumination low-coherence interferometry

      We present a method to image refractive index distribution within a sample across 8 mm dimension with high spatial resolution by a transmission low-coherence interferometer. The relative strong forward-scattering light is collected, from which the parallel projections of refractive indices within the sample are obtained. A convolution backprojection algorithm is used to transform the projection data set recorded at sufficient angular views into the spatial distribution of refractive indices within the sample. We experimentally demonstrate this method by imaging a phantom. We show that this method can achieve a precision of 0.01 in determining the refractive index and a ...

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    24. Optical coherence tomography endoscopic imaging system using mini-ultrasonic motor

      Qiao Li, Changlei Gao, Yi Wang et al. Optical coherence tomography(OCT) is a new non-invasive, cross-sectional imaging technique that measures depth resolved reflectance of tissue by employing low-coherence interferometer. The acquisition of the signal may be achieved either in the time domain(TD) by altering the reference arm length of ... [Proc. SPIE Int. Soc. Opt. Eng. 6826, 682607 (2008)] published Tue Jan 8, 2008.

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      Mentions: Yi Wang
    1-25 of 25
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    High-resolution computed tomography of refractive index distribution by transillumination low-coherence interferometry Autocorrelation optical coherence tomography for mapping transverse particle-flow velocity Measurement of particle concentration in flow by statistical analyses of optical coherence tomography signals Noncontact photoacoustic imaging achieved by using a low-coherence interferometer as the acoustic detector Resolution Improvement with Two-Dimensional Digital Focusing Method in Optical Coherence Tomography Practical approach for dispersion compensation in spectral-domain optical coherence tomography Measurement of wall shear stress in chick embryonic heart using optical coherence tomography All-optically integrated photo-acoustic microscopy and optical coherence tomography based on a single Michelson detector In vivo assessment of wall strain in embryonic chick heart by spectral domain optical coherence tomography A case report of a coronary myocardial bridge with impaired full-cycle ratio during dobutamine challenge Diagnosis of chronic stage of hypertensive retinopathy based on spectral domain optical coherence tomography A Cross-sectional Optical Coherence Tomography Study in Patients on Taxane-based Therapy and A Case Report with the Literature Review