1. Articles from Ruikang Wang

    1-24 of 30 1 2 »
    1. Development of a clinical prototype of a miniature hand-held optical coherence tomography probe for prematurity and pediatric ophthalmic imaging

      Development of a clinical prototype of a miniature hand-held optical coherence tomography probe for prematurity and pediatric ophthalmic imaging

      We report a novel design and operation of a highly integrated miniature handheld OCT probe, with high-speed angiography function that can be used in clinical settings for young children and infants, providing rapid, non-invasive structural and angiographic imaging of the retina and choroid. The imaging system is operated at 200 kHz, with 3D OCT and OCTA scan time of 0.8 and 3.2 seconds, respectively, and the scanning angle on the pupil is ± 36°, covering the full perifoveal region. Operator assisting features of the direct-view iris camera and on-probe display are integrated into the hand-held probe, and the fixation ...

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    2. Microvascular imaging of the skin

      Microvascular imaging of the skin

      Despite our understanding that the microvasculature plays a multifaceted role in the development and progression of various conditions, we know little about the extent of this involvement. A need exists for non-invasive, clinically meaningful imaging modalities capable of elucidating microvascular information to aid in our understanding of disease, and to aid in the diagnosis/monitoring of disease for more patient-specific care. In this review article, a number of imaging techniques are summarized that have been utilized to investigate the microvasculature of skin, along with their advantages, disadvantages and future perspectives in preclinical and clinical settings. These techniques include dermoscopy, capillaroscopy ...

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    3. Age-Dependent Changes in the Macular Choriocapillaris of Normal Eyes Imaged with Swept-Source OCT Angiography

      Age-Dependent Changes in the Macular Choriocapillaris of Normal Eyes Imaged with Swept-Source OCT Angiography

      Purpose Swept source optical coherence tomography angiography (SS-OCTA) was used to measure the age-dependent changes in macular choriocapillaris (CC) flow deficits (FDs) in normal eyes. Design A prospective, cross-sectional study. Methods Subjects with normal eyes ranging in age from their 20s to their 80s were imaged using a 100-kHz SS-OCTA instrument (PLEX ® Elite 9000, Carl Zeiss Meditec). Both 3x3 mm and 6x6 mm scans were used to image the macular CC. Visualization of the CC and quantification of FDs were performed using a previously validated algorithm. The percentage of FDs (FD%) in the central 1 mm circle (C 1 ), 1 ...

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    4. Special Section Guest Editorial: Commemorating 25 Years of Optical Coherence Tomography: a Perspective on Biomedical Applications

      Special Section Guest Editorial: Commemorating 25 Years of Optical Coherence Tomography: a Perspective on Biomedical Applications

      ptical coherence tomography (OCT) has become a major medical imaging technology in the time since its inception now more than 25 years ago. During this time, OCT has become very well established in ophthalmology, and this application area largely dominates the field. Next in importance and stage of development is cardiovascular medicine, also a strongly commercial technology, but at an earlier stage and a slower pace of uptake than ophthalmology. Other application areas are generally less well developed, but continue to grow, and new opportunities continue to emerge across a wide range of topics, including beyond medicine and biology. In ...

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    5. Flexible wide-field optical micro-angiography based on Fourier-domain multiplexed dual-beam swept source optical coherence tomography

      Flexible wide-field optical micro-angiography based on Fourier-domain multiplexed dual-beam swept source optical coherence tomography

      Wide-field optical coherence tomography angiography (OCTA) is gaining interest in clinical imaging applications. In this pursuit, it is challenging to maintain the imaging resolution and sensitivity throughout the wide field of view (FoV). Here, we propose a novel method/system of dual-beam arrangement and Fourier domain multiplexing to achieve wide field OCTA when imaging the uneven surface samples. The proposed system provides two separate FoVs, with flexibility that the imaging area, focus of the imaging beam and imaging depth range can be individually adjusted for each FoV, leading to either 1) increased system imaging FoV or 2) capability of targeting ...

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    6. Methods of reducing motion artifacts for optical coherence tomography angiography

      Methods of reducing motion artifacts for optical coherence tomography angiography

      A method for reducing motion artifacts in optical coherence tomography (OCT) angiography images is disclosed. The method is applied to the intensity or complex OCT data prior to applying the motion contrast analysis and involves determining sub-pixel level shifts between at least two B-scans repeated approximately at the same location and applying the sub-pixel level shifts to the B-scans to be able to correct for motion and accurately determine motion contrast signal. A preferred embodiment includes the use of 2D cross correlations to register a series of B-scans in both the axial (z-) and lateral (x-) dimensions and a convolution ...

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    7. Imaging collector channel entrance with a new intraocular micro-probe swept-source optical coherence tomography

      Imaging collector channel entrance with a new intraocular micro-probe swept-source optical coherence tomography

      Purpose To describe the use of a newly developed side-viewing catheter probe to provide the cross-sectional images of collector channel entrance (CCE), achieved by swept-source optical coherence tomography (SS-OCT). Methods A side-viewing SS-OCT catheter probe was developed that has a core probe diameter of 0.15 mm and an outer diameter of 0.25 mm, for the purpose of imaging CCEs within eye globe. Cadaver eyes harvested from swine and human were used to demonstrate its feasibility. For porcine eyes, the probe imaged the CCE by accessing the region of the aqueous plexus (AP) as well as along the inner ...

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    8. Quantitative measurement and real-time tracking of high intensity focused ultrasound using phase-sensitive optical coherence tomography: Feasibility study

      Quantitative measurement and real-time tracking of high intensity focused ultrasound using phase-sensitive optical coherence tomography: Feasibility study

      Purpose: Phase-sensitive optical coherence tomography (PhS-OCT) is proposed, as a new high intensity focused ultrasound (HIFU) imaging guidance to detect and track HIFU focus inside 1% agar samples in this work. The experiments studied the effect of varying HIFU power on the induction of shear wave, which can be implemented as a new technique to monitor focused ultrasound surgery (FUS). Method: A miniature HIFU transducer (1.02 MHz, 20 mm aperture diameter, 15 mm radius of curvature) was produced in-house, pressure-field mapped, and calibrated. The transducer was then embedded inside a 1% agar phantom, which was placed under PhS-OCT for ...

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    9. 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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    10. 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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    11. Elasticity imaging of speckle-free tissue regions with moving acoustic radiation force and phase-sensitive optical coherence tomography

      Elasticity imaging of speckle-free tissue regions with moving acoustic radiation force and phase-sensitive optical coherence tomography

      Phase-sensitive optical coherence tomography (PhS-OCT) can be utilized for quantitative shear-wave elastography using speckle tracking. However, current approaches cannot directly reconstruct elastic properties in speckle-less or speckle-free regions, for example within the crystalline lens in ophthalmology. Investigating the elasticity of the crystalline lens could improve understanding and help manage presbyopia-related pathologies that change biomechanical properties. We propose to reconstruct the elastic properties in speckle-less regions by sequentially launching shear waves with moving acoustic radiation force (mARF), and then detecting the displacement at a specific speckle-generating position, or limited set of positions, with PhS-OCT. A linear ultrasound array (with a center ...

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    12. Minimally invasive surgical method to detect sound processing in the cochlear apex by optical coherence tomography

      Minimally invasive surgical method to detect sound processing in the cochlear apex by optical coherence tomography

      Sound processing in the inner ear involves separation of the constituent frequencies along the length of the cochlea. Frequencies relevant to human speech (100 to 500 Hz) are processed in the apex region. Among mammals, the guinea pig cochlear apex processes similar frequencies and is thus relevant for the study of speech processing in the cochlea. However, the requirement for extensive surgery has challenged the optical accessibility of this area to investigate cochlear processing of signals without significant intrusion. A simple method is developed to provide optical access to the guinea pig cochlear apex in two directions with minimal surgery ...

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    13. Development of a phase-sensitive Fourier domain optical coherence tomography system to measure mouse organ of Corti vibrations in two cochlear turns

      Development of a phase-sensitive Fourier domain optical coherence tomography system to measure mouse organ of Corti vibrations in two cochlear turns

      In this study, we have developed a phase-sensitive Fourier-domain optical coherence tomography system to simultaneously measure the in vivo inner ear vibrations in the hook area and second turn of the mouse cochlea. This technical development will enable measurement of intra-cochlear distortion products at ideal locations such as the distortion product generation site and reflection site. This information is necessary to un-mix the complex mixture of intra-cochlear waves comprising the DPOAE and thus leads to the non-invasive identification of the local region of cochlear damage.

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    14. Moving beam shear wave reconstruction for both ultrasound and optical coherence tomography applications

      Moving beam shear wave reconstruction for both ultrasound and optical coherence tomography applications

      Shear wave elasticity imaging can quantitatively estimate a stiffness map of biological tissues based on speckle-tracking shear wave propagation. However, current approaches cannot directly reconstruct elasticity properties in speckle-less or speckle-free regions, for example within the crystalline lens in ophthalmology. We propose an imaging sequence to reconstruct the elastic properties in speckle-free regions by sequentially launching shear waves with a laterally moving acoustic radiation force, and then detecting the displacement at a specific speckle-generating position. The imaging sequence was tested for both ultrasound and phase-sensitive optical coherence tomography imaging. Tissue-mimicking phantom studies were performed and results demonstrate that elastic properties ...

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    15. Lymphatic response to depilation-induced inflammation in mouse ear assessed with label-free optical lymphangiography

      Lymphatic response to depilation-induced inflammation in mouse ear assessed with label-free optical lymphangiography

      Background and Objectives Optical microangiography (OMAG) is a noninvasive technique capable of imaging 3D microvasculature. OMAG-based optical lymphangiography has been developed for 3D visualization of lymphatic vessels without the need for exogenous contrast agents. In this study, we utilize the optical lymphangiography to investigate dynamic changes in lymphatic response within skin tissue to depilation-induced inflammation by using mouse ear as a simple tissue model. Materials and Methods A spectral-domain optical coherence tomography (OCT) system is used in this study to acquire volumetric images of mouse ear. The system operates under the ultrahigh-sensitive OMAG scanning protocol with five repetitions for each ...

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    16. Polarization sensitive spectral domain OCT using an interference signal modulated at a constant frequency and a two-path reference arm with a single reference mirror

      Polarization sensitive spectral domain OCT using an interference signal modulated at a constant frequency and a two-path reference arm with a single reference mirror

      Embodiments include apparatuses and methods for spectral domain polarization sensitive optical coherence tomography including a reference assembly for detection of the polarization sensitive spectral interferograms formed by vertically and horizontally polarized beam components. Interference signals between the reference and sample beams may be modulated at a constant frequency.

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    17. Two dimensional vibrations of the guinea pig apex organ of Corti measured in vivo using phase sensitive Fourier domain optical coherence tomography

      Two dimensional vibrations of the guinea pig apex organ of Corti measured in vivo using phase sensitive Fourier domain optical coherence tomography

      In this study, we measure the in vivo apical-turn vibrations of the guinea pig organ of Corti in both axial and radial directions using phase-sensitive Fourier domain optical coherence tomography. The apical turn in guinea pig cochlea has best frequencies around 100 – 500 Hz which are relevant for human speech. Prior measurements of vibrations in the guinea pig apex involved opening the otic capsule, which has been questioned on the basis of the resulting changes to cochlear hydrodynamics. Here this limitation is overcome by measuring the vibrations through bone without opening the otic capsule. Furthermore, we have significantly reduced the ...

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    18. MEMS scanning micromirror for optical coherence tomography

      MEMS scanning micromirror for optical coherence tomography

      This paper describes an endoscopic-inspired imaging system employing a micro-electromechanical system (MEMS) micromirror scanner to achieve beam scanning for optical coherence tomography (OCT) imaging. Miniaturization of a scanning mirror using MEMS technology can allow a fully functional imaging probe to be contained in a package sufficiently small for utilization in a working channel of a standard gastroesophageal endoscope. This work employs advanced image processing techniques to enhance the images acquired using the MEMS scanner to correct non-idealities in mirror performance. The experimental results demonstrate the effectiveness of the proposed technique.

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    19. Noninvasive Imaging of Retinal Morphology and Microvasculature in Obese Mice using Optical Coherence Tomography and Optical Microangiography

      Noninvasive Imaging of Retinal Morphology and Microvasculature in Obese Mice using Optical Coherence Tomography and Optical Microangiography

      Purpose:To evaluate early diabetes-induced changes in retinal thickness and microvasculature in a type II diabetic mouse model using OCT/OMAG. Methods:22 week old obese BTBR mice (OB, n=10) and wild type control mice (WT, n=10) were imaged. Three-dimensional data were captured with OCT using an ultrahigh sensitive OMAG scanning protocol for 3D angiography of the retina and dense A-scan protocol for measurement of the total retinal blood flow (RBF) rate. The thickness of the nerve fiber layer (NFL) and NFL to inner plexiform layer (IPL) were measured and compared between OB and WT mice. The linear ...

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    20. Methods And Systems For Imaging Tissue Motion Using Optical Coherence Tomography

      Methods And Systems For Imaging Tissue Motion Using Optical Coherence Tomography

      A system and method for measuring tissue motion within a living tissue of the anterior segment and aqueous outflow system of the eye in a subject are provided. Tissue movements are extracted from a plurality of images acquired from the living tissue using an optical coherence tomography system. The images may be corrected using motion compensation. To extract the tissue movements from the images, waves from a cardiac pulse or other externally induced pulses from the subject are acquired, and a pulse wave is defined for a given time, which is then correlated with a velocity wave defined for a ...

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    21. Measurement of in vivo basal-turn vibrations of the organ of Corti using phase-sensitive Fourier domain optical coherence tomography

      Measurement of in vivo basal-turn vibrations of the organ of Corti using phase-sensitive Fourier domain optical coherence tomography

      A major reason we can perceive faint sounds and communicate in noisy environments is that the outer hair cells of the organ of Corti enhance the sound-evoked motions inside the cochlea. To understand how the organ of Corti works, we have built and tested the phase-sensitive Fourier domain optical coherence tomography (PSFDOCT) system. This system has key advantages over our previous time domain OCT system [1]. The PSFDOCT system has better signal to noise and simultaneously acquires vibration data from all points along the optical-axis [2]. Feasibility of this system to measure in vitro cochlear vibrations in the apex was ...

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    22. Biomechanics of the Chick Embryonic Heart Outflow Tract at HH18 Using 4D Optical Coherence Tomography Imaging and Computational Modeling

      Biomechanics of the Chick Embryonic Heart Outflow Tract at HH18 Using 4D Optical Coherence Tomography Imaging and Computational Modeling

      During developmental stages, biomechanical stimuli on cardiac cells modulate genetic programs, and deviations from normal stimuli can lead to cardiac defects. Therefore, it is important to characterize normal cardiac biomechanical stimuli during early developmental stages. Using the chicken embryo model of cardiac development, we focused on characterizing biomechanical stimuli on the Hamburger–Hamilton (HH) 18 chick cardiac outflow tract (OFT), the distal portion of the heart from which a large portion of defects observed in humans originate. To characterize biomechanical stimuli in the OFT, we used a combination of in vivo optical coherence tomography (OCT) imaging, physiological measurements and computational ...

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    23. 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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    24. Feature Of The Week 6/17/12: Middle Ear Vibrometry of Human Cadaver Temporal Bone with Spectral Domain Phase-Sensitive Optical Coherence Tomography

      Feature Of The Week 6/17/12: Middle Ear Vibrometry of Human Cadaver Temporal Bone with Spectral Domain Phase-Sensitive Optical Coherence Tomography

      Hearing loss is the most frequent sensory deficit in the human population, affecting more than 250 million people in the world. The National Center for Health Statistics estimates that 37 million adults (17%) in the United States have hearing difficulty. Analysis of a large database of audiometric records from the University of Minnesota reveals that 39% of patients diagnosed with hearing loss have conductive hearing loss (CHL) either alone (15%) or in combination with SNHL (24%). There are several contemporary audiological tests that are commonly used to diagnose middle ear function for CHL. However, these contemporary tests of middle ear ...

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    1-24 of 30 1 2 »
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    1. (30 articles) Ruikang K. Wang
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    High-speed, full-range optical coherence tomography Visualizing ocular perfusion with optical microangiography Autocorrelation optical coherence tomography for mapping transverse particle-flow velocity A tomography system for imaging deep tissues High speed spectral domain optical coherence tomography for retinal imaging at 500,000 A‑lines per second Feature Of The Week 6/17/12: Middle Ear Vibrometry of Human Cadaver Temporal Bone with Spectral Domain Phase-Sensitive Optical Coherence Tomography Quantifying Optical Microangiography Images Obtained from a Spectral Domain Optical Coherence Tomography System Biomechanics of the Chick Embryonic Heart Outflow Tract at HH18 Using 4D Optical Coherence Tomography Imaging and Computational Modeling Measurement of in vivo basal-turn vibrations of the organ of Corti using phase-sensitive Fourier domain optical coherence tomography Physical Sciences Receives NIH Grant for Optical Prove for Real-Time Assessment of Periodontal Health Status Direct synthesis of water-dispersible magnetic/plasmonic hetero-nanostructures for multi-modality biomedical imaging Quantitative evaluation of primary retinitis pigmentosa patients using colour Doppler flow imaging and optical coherence tomography angiography