1. Articles from Cuixia Dai

    1-22 of 22
    1. Imaging depth extension of optical coherence tomography in rabbit eyes using optical clearing agents

      Imaging depth extension of optical coherence tomography in rabbit eyes using optical clearing agents

      Optical coherence tomography has become an indispensable diagnostic tool in ophthalmology for imaging the retina and the anterior segment of the eye. However, the imaging depth of optical coherence tomography is limited by light attenuation in tissues due to optical scattering and absorption. In this study of rabbit eye both ex vivo and in vivo , optical coherence tomography imaging depth of the anterior and posterior segments of the eye was extended by using optical clearing agents to reduce multiple scattering. The sclera, the iris, and the ciliary body were clearly visualized by direct application of glycerol at an incision on ...

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    2. In vivo time-serial evaluation of laser-induced choroidal neovascularization in rats simultaneously using photoacoustic microscopy and optical coherence tomography

      In vivo time-serial evaluation of laser-induced choroidal neovascularization in rats simultaneously using photoacoustic microscopy and optical coherence tomography

      Determination of the precise location and degree of condition of the Choroidal neovascularization (CNV) lesion is essential for diagnosation Neovascular age-related macular degeneration (AMD) and evaluation the efficacy of treatment. Given the complimentary contrast mechanisms of Photoacoustic microscopy (PAM) and Optical coherence tomography (OCT), the combination of PAM and OCT imaging could potentially provide much sensitive and specific detection of CNV. In this paper, we validated the opportunity to evaluate the information of laser-induced CNV and presented the in vivo time-serial evaluation of the CNV by simultaneously using PAM and OCT techniques. In vivo PAM and OCT examination was performed ...

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    3. Retinal pulse wave velocity measurement using spectral-domain optical coherence tomography

      Retinal pulse wave velocity measurement using spectral-domain optical coherence tomography

      The human eyes provide a natural window for noninvasive measurement of the pulse wave velocity (PWV) of small arteries. By measuring the retinal PWV, the stiffness of small arteries can be assessed, which may better detect early vascular diseases. Therefore, retinal PWV measurement has attracted increasing attention. In this study, a jump-scanning method was proposed for non-invasive measurement of retinal PWV using spectral-domain OCT. The jump-scanning method uses the phase-resolved Doppler OCT to obtain the pulse shapes. To realize PWV measurement, the jump-scanning method extracts the transit time of the pulse wave from an original OCT scanning site to another ...

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    4. Miniature probe for mapping mechanical properties of vascular lesions using acoustic radiation force optical coherence elastography

      Miniature probe for mapping mechanical properties of vascular lesions using acoustic radiation force optical coherence elastography

      Cardiovascular diseases are the leading cause of fatalities in the United States. Atherosclerotic plaques are one of the primary complications that can lead to strokes and heart attacks if left untreated. It is essential to diagnose the disease early and distinguish vulnerable plaques from harmless ones. Many methods focus on the structural or molecular properties of plaques. Mechanical properties have been shown to change drastically when abnormalities develop in arterial tissue. We report the development of an acoustic radiation force optical coherence elastography (ARF-OCE) system that uses an integrated miniature ultrasound and optical coherence tomography (OCT) probe to map the ...

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    5. Volumetric vessel reconstruction method for absolute blood flow velocity measurement in Doppler OCT images

      Volumetric vessel reconstruction method for absolute blood flow velocity measurement in Doppler OCT images

      Doppler optical coherence tomography (DOCT) is considered one of the most promising functional imaging modalities for neuro biology research and has demonstrated the ability to quantify cerebral blood flow velocity at a high accuracy. However, the measurement of total absolute blood flow velocity (BFV) of major cerebral arteries is still a difficult problem since it not only relates to the properties of the laser and the scattering particles, but also relates to the geometry of both directions of the laser beam and the flow. In this paper, focusing on the analysis of cerebral hemodynamics, we presents a method to quantify ...

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    6. 3D mapping of elastic modulus using shear wave optical micro-elastography

      3D mapping of elastic modulus using shear wave optical micro-elastography

      lastography provides a powerful tool for histopathological identification and clinical diagnosis based on information from tissue stiffness. Benefiting from high resolution, three-dimensional (3D), and noninvasive optical coherence tomography (OCT), optical micro-elastography has the ability to determine elastic properties with a resolution of ~10 μm in a 3D specimen. The shear wave velocity measurement can be used to quantify the elastic modulus. However, in current methods, shear waves are measured near the surface with an interference of surface waves. In this study, we developed acoustic radiation force (ARF) orthogonal excitation optical coherence elastography (ARFOE-OCE) to visualize shear waves in 3D. This ...

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    7. Acoustic Radiation Force Optical Coherence Elastography of Corneal Tissue

      Acoustic Radiation Force Optical Coherence Elastography of Corneal Tissue

      We report on a real-time acoustic radiation force optical coherence elastography (ARF-OCE) system to map the relative elasticity of corneal tissue. A modulated ARF is used as excitation to vibrate the cornea, while OCE serves as detection of tissue response. To show feasibility of detecting mechanical contrast using this method, we performed tissue-equivalent agarose phantom studies with inclusions of a different stiffness. We obtained 3-D elastograms of a healthy cornea and a highly cross-linked cornea. Finally, we induced a stiffness change on a small portion of a cornea and observed the differences in displacement.

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    8. Fully distributed absolute blood flow velocity measurement for middle cerebral arteries using Doppler optical coherence tomography

      Fully distributed absolute blood flow velocity measurement for middle cerebral arteries using Doppler optical coherence tomography

      Doppler optical coherence tomography (DOCT) is considered one of the most promising functional imaging modalities for neuro biology research and has demonstrated the ability to quantify cerebral blood flow velocity at a high accuracy. However, the measurement of total absolute blood flow velocity (BFV) of major cerebral arteries is still a difficult problem since it is related to vessel geometry. In this paper, we present a volumetric vessel reconstruction approach that is capable of measuring the absolute BFV distributed along the entire middle cerebral artery (MCA) within a large field-of-view. The Doppler angle at each point of the MCA, representing ...

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    9. Automatic airway wall segmentation and thickness measurement for long-range optical coherence tomography images

      Automatic airway wall segmentation and thickness measurement for long-range optical coherence tomography images

      We present an automatic segmentation method for the delineation and quantitative thickness measurement of multiple layers in endoscopic airway optical coherence tomography (OCT) images. The boundaries of the mucosa and the sub-mucosa layers are accurately extracted using a graph-theory-based dynamic programming algorithm. The algorithm was tested with sheep airway OCT images. Quantitative thicknesses of the mucosal layers are obtained automatically for smoke inhalation injury experiments.

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    10. Dual band dual focus optical coherence tomography for imaging the whole eye segment

      Dual band dual focus optical coherence tomography for imaging the whole eye segment

      We developed an improved dual band dual focus spectral domain optical coherence tomography (SD-OCT) for in vivo 2D/3D imaging of the whole eye segment, including the whole anterior segment and retina. The system featured two OCT channels with two different bands centered at 840 nm and 1050 nm, which were designed to image the retina and the anterior segments of the eye, respectively. By combing the two probe light beams for co-axial scanning and separating them for focusing at different segments of the eye with a combination of three dichroic mirrors, we not only minimized the loss of the ...

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    11. Whole Eye Segment Imaging and Measurement With Dual-Channel Spectral-Domain OCT

      Whole Eye Segment Imaging and Measurement With Dual-Channel Spectral-Domain OCT

      BACKGROUND AND OBJECTIVES: To image and measure whole eye segments using dual-channel spectral-domain optical coherence tomography (SD-OCT) and to compare the results with those from the IOLMaster (Carl Zeiss Meditec, Dublin, CA). PATIENTS AND METHODS: Twenty eyes of 20 volunteers were recruited. Ocular dimensions, including cornea thickness, anterior chamber depth (ACD), lens thickness, anterior lens surface curvature, and axial length (AL), were calculated. The reproducibility of SD-OCT measurements, statistical significance of inter-instrument difference, correlation, and agreement were evaluated. RESULTS: No significant differences were found between independent SD-OCT measurements ( P > .05). The ACD and AL measured with IOLMaster were significantly shorter ...

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    12. Dual illumination OCT at 1050nm and 840nm for whole eye segment imaging

      Dual illumination OCT at 1050nm and 840nm for whole eye segment imaging

      We presented an improved dual channel dual focus spectral domain optical coherence tomography (SD-OCT) with two illuminations at 840 nm and 1050 nm for whole eye segment imaging and biometry in vivo. The two light beams were coupled and optically optimized to scan the anterior and posterior segment of the eye simultaneously. This configuration with dichroic mirrors integrated in the sample arm enables us to acquire images from the anterior segment and retina effectively with minimum loss of sample signal. In addition, the full resolved complex (FRC) method was applied to double the imaging depth for the whole anterior segment ...

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    13. Accommodation-induced variations in retinal thickness measured by spectral domain optical coherence tomography

      Accommodation-induced variations in retinal thickness measured by spectral domain optical coherence tomography

      To research retinal stretching or distortion with accommodation, accommodation-induced changes in retinal thickness (RT) in the macular area were investigated in a population of young adults ( n = 23 ) by using a dual-channel spectral domain optical coherence tomography (SD-OCT) system manufactured in-house for this study. This dual-channel SD-OCT is capable of imaging the cornea and retina simultaneously with an imaging speed of 24 kHz A-line scan rate, which can provide the anatomical dimensions of the eye, including the RT and axial length. Thus, the modification of the RT with accommodation can be calculated. A significant decrease in the RT ( 13.50 ...

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    14. Dual-channel spectral-domain optical-coherence tomography system based on 3 × 3 fiber coupler for extended imaging range

      Dual-channel spectral-domain optical-coherence tomography system based on 3 × 3 fiber coupler for extended imaging range

      We have demonstrated a dual-channel multiplexing spectral-domain optical-coherence tomography (SD-OCT) system based on a 3 × 3 fiber coupler for extended imaging range of whole human eye depth, with a single light source and spectrometer. OCT images of anterior segments of a human eye were sequentially performed and constructed to demonstrate an extended depth range as large as 15 mm in air. A good quality OCT image of the whole anterior segment of an eye was present. Furthermore, whole eye segmental imaging was performed and ocular distances were calculated to show the validation of the system for whole eye morphological measurement.

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    15. Virtual-OCT: A simulated optical coherence tomography instrument

      Virtual-OCT: A simulated optical coherence tomography instrument

      We report the virtual instrumentation of both time-domain (TD) and spectral-domain (SD) optical coherence tomography (OCT) systems. With a virtual partial coherence source from either a simulated or measured spectrum, the OCT signals of both A-scan and B-scan were demonstrated. The spectrometric detector's pixel number, dynamic range, noise, as well as spectral resolution can be simulated in the virtual spectral domain (SD-OCT). The virtual-OCT system provides an environment for parameter evaluation and algorithm optimization for experimental OCT instrumentation, and promotes the understanding of OCT imaging and signal post-processing processes.

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    16. Absolute retinal blood flow measurement with a dual-beam Doppler optical coherence tomography

      Absolute retinal blood flow measurement with a dual-beam Doppler optical coherence tomography

      Purpose:To test the capability of a novel dual-beam Doppler optical coherence tomography (OCT) technique for simultaneous in vivo measurement of the Doppler angle and, thus, the absolute retinal blood velocity and the retinal flow rate, without the influence of motion artifacts. Methods:A novel dual-beam Doppler spectral domain OCT (SD-OCT) was developed. The two probing beams are separated with a controllable distance along an arbitrary direction, both of which are controlled by two independent 2D optical scanners. Two sets of optical Doppler tomography (ODT) images are acquired simultaneously. The Doppler angle of each blood vessel segment was calculated from ...

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    17. Noninvasive Imaging and Measurement of Accommodation Using Dual-Channel SD-OCT

      Noninvasive Imaging and Measurement of Accommodation Using Dual-Channel SD-OCT

      Purpose : To investigate the feasibility and practicality of real-time noninvasive imaging and measurement of ocular accommodation (0–5D with one diopter step) using dual-channel , dual-focus spectral domain optical coherence tomography ( SD-OCT ). Materials and Methods : A custom-built, dual-channel , dual-focus SD-OCT was used to image the anterior segment, including the cornea, iris, and anterior and posterior lens surfaces. Three consecutive measurements were taken in each accommodative session for each subject. Changes in ocular dimensions during accommodation were calculated based on the acquired SD-OCT images . A Friedman test was used to test sensitivity of ocular dimension changes per diopter of accommodation . Results : With ...

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    18. Effect of Contact Lens on Optical Coherence Tomography Imaging of Rodent Retina

      Effect of Contact Lens on Optical Coherence Tomography Imaging of Rodent Retina

      Visibility of optical coherence tomography (OCT) images can be severely degraded by speckle noise. A computationally efficient despeckling approach that strongly reduces the speckle noise is reported. It is based on discrete wavelet transform (DWT), but eliminates the conventional process of threshold estimation. By decomposing an image into different levels, a set of sub-band images are generated, where speckle noise is additive. These sub-band images can be compounded to suppress the additive speckle noise, as DWT coefficients resulting from speckle noise tend to be approximately decorrelated. The final despeckled image is reconstructed by taking the inverse wavelet transform of the ...

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    19. Simultaneous optical coherence tomography and autofluorescence microscopy with a single light source

      Simultaneous optical coherence tomography and autofluorescence microscopy with a single light source

      We have accomplished simultaneous spectral domain optical coherence tomography (SD-OCT) and autofluorescence (AF) microscopy with a broadband light source centered at 415 nm. The light source was provided by frequency-doubling of an ultra-fast broadband Ti:Sapphire laser. With a bandwidth of 8 nm, the visible SD-OCT achieved a depth resolution of ∼ 12  μm. Since the two imaging modalities are provided by the same group of photons, their images are intrinsically registered. The dual-modal system is capable of providing OCT imaging and molecular contrasts simultaneously. The imaging system was tested on imaging biological samples ex vivo and in vivo

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    20. Feature Of The Week 3/18/12: Research Results from Shanghai Jiaotong University on Optical Coherence Tomography for Whole Eye Segment Imaging

      Feature Of The Week 3/18/12: Research Results from Shanghai Jiaotong University on Optical Coherence Tomography for Whole Eye Segment Imaging

      Researchers from Shanghai Jiao Tong University, Shanghai Institute of Technology, Peking University, and UCLA recently published a paper on “Optical coherence tomography for whole eye segment imaging". Below is a summary of their work. We proposed a dual focus dual channel spectral domain optical coherence tomography (SD-OCT) for simultaneous imaging of the whole eye segments from cornea to the retina. By using dual channels the system solved the problem of limited imaging depth of SD-OCT. By using dual focus the system solved the problem of simultaneous light focusing on the anterior segment of the eye and the retina. Dual focusing ...

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    21. Optical coherence tomography for whole eye segment imaging

      Optical coherence tomography for whole eye segment imaging

      We proposed a dual focus dual channel spectral domain optical coherence tomography (SD-OCT) for simultaneous imaging of the whole eye segments from cornea to the retina. By using dual channels the system solved the problem of limited imaging depth of SD-OCT. By using dual focus the system solved the problem of simultaneous light focusing on the anterior segment of the eye and the retina. Dual focusing was achieved by adjusting the collimating lenses so the divergence of the two probing beams was tuned to make them focused at different depth in the eye. We further achieved full range complex (FRC ...

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    22. In-vivo full depth of eye imaging spectral domain optical coherence tomography

      In-vivo full depth of eye imaging spectral domain optical coherence tomography

      It is necessary to apply the spectral-domain optical coherence tomography (SD-OCT) to image the whole eye segment for practically iatrical application, but the imaging depth of SD-OCT is limited by the spectral resolution of the spectrometer. By now, no result about this research has been reported. In our study, a new dual channel dual focus OCT system is adopted to image the whole eye segment. The cornea and the crystalline lens are simultaneously imaged by using full range complex spectral-domain OCT in one channel, the retina is detected by the other. The new system was successfully tested in imaging of ...

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    1-22 of 22
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    In-vivo full depth of eye imaging spectral domain optical coherence tomography Optical coherence tomography for whole eye segment imaging Feature Of The Week 3/18/12: Research Results from Shanghai Jiaotong University on Optical Coherence Tomography for Whole Eye Segment Imaging Simultaneous optical coherence tomography and autofluorescence microscopy with a single light source Effect of Contact Lens on Optical Coherence Tomography Imaging of Rodent Retina Noninvasive Imaging and Measurement of Accommodation Using Dual-Channel SD-OCT Absolute retinal blood flow measurement with a dual-beam Doppler optical coherence tomography Virtual-OCT: A simulated optical coherence tomography instrument Dual-channel spectral-domain optical-coherence tomography system based on 3 × 3 fiber coupler for extended imaging range Dual band dual focus optical coherence tomography for imaging the whole eye segment Fantom Encore Sirolimus-eluting Bioresorbable Scaffold for Treatment of De-novo CAD: the ENCORE-I Study Assessment of Microcirculatory Dysfunction in Septic Shock Patients by OCTA