1. Articles from Xinwen Yao

    1-20 of 20
    1. Quantitative Microvascular Analysis With Wide-Field Optical Coherence Tomography Angiography in Eyes With Diabetic Retinopathy

      Quantitative Microvascular Analysis With Wide-Field Optical Coherence Tomography Angiography in Eyes With Diabetic Retinopathy

      Importance Wide-field optical coherence tomographic angiography (OCTA) may provide insights to peripheral capillary dropout in eyes with diabetic retinopathy (DR). Objective To describe the diagnostic performance of wide-field OCTA with and without large vessel removal for assessment of DR in persons with diabetes. Design, Setting, and Participants This case-control study was performed from April 26, 2018, to April 8, 2019, at a single tertiary eye center in Singapore. Case patients were those with type 2 diabetes for more than 5 years and bilateral DR diagnosed by fundus imaging; control participants included those with no self-reported history of diabetes, a fasting ...

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    2. Ultra-sensitive optical coherence elastography using a high-dynamic-range force loading scheme for cervical rigidity assessment

      Ultra-sensitive optical coherence elastography using a high-dynamic-range force loading scheme for cervical rigidity assessment

      An ultra-sensitive, wide-range force loading scheme is proposed for compression optical coherence elastography (OCE) that allows for the quantitative analysis of cervical tissue elasticity ex vivo . We designed a force loading apparatus featuring a water sink for minuscule incremental loading through a volume-controlled water droplet, from which the Young’s modulus can be calculated by fitting the stress-strain curve. We validated the performance of the proposed OCE system on homogenous agar phantoms, showing the Young’s modulus can be accurately estimated using this scheme. We then measured the Young’s modulus of rodent cervical tissues acquired at different gestational ages ...

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    3. Beyond Fourier transform: break the axial resolution limit in optical coherence tomography

      Beyond Fourier transform: break the axial resolution limit in optical coherence tomography

      Optical coherence tomography (OCT) is a volumetric imaging modality that empowers the clinicians and scientists to noninvasively visualize and examine the microscopic cross-sectional architectures of biological samples. By taking advantages of the coherence gating, OCT could achieve micrometer-level axial sectioning with high sensitivity. In the past decade, substantial efforts have been made to push the axial resolution of Fourier-domain OCT (FD-OCT) further into the sub-micron regime via physically extending the system’s spectral bandwidth. Here, we would like to offer a new perspective on this problem. We argue that the coupling between the axial resolution and the spectral bandwidth in ...

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    4. High-sensitive swept-source optical coherence tomography system and methods of use thereof

      High-sensitive swept-source optical coherence tomography system and methods of use thereof

      An exemplary system can be provided which can include, for example, a plurality of source arrangements configured to provide a plurality of electro-magnetic radiations to at least one of at least one sample or at least one reference structure, a first arrangement configured to receive a first radiation(s) from the reference structure(s), a second arrangement configured to receive a second radiation(s) from the sample(s), where a portion(s) of the second radiation(s) can be in an invisible spectrum, a third arrangement configured to combine the first radiation(s) and the second radiation(s) into a ...

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    5. On-chip tunable photonic delay line

      On-chip tunable photonic delay line

      An on-chip tunable photonic delay line is a key building block for applications including sensing, imaging, and optical communication. However, achieving long and tunable delay lines within a small footprint remains challenging. Here, we demonstrate an on-chip tunable photonic delay line using ultralow loss high confinement Si 3 N 4 waveguides with integrated microheaters. As an example of potential application, we embed a 0.4 m delay line within an optical coherence tomography (OCT) system. We show that the delay line can extend the OCT imaging range by 0.6 mm while maintaining a high signal to noise ratio. Our ...

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    6. Fully Automated Postlumpectomy Breast Margin Assessment Utilizing Convolutional Neural Network Based Optical Coherence Tomography Image Classification Method

      Fully Automated Postlumpectomy Breast Margin Assessment Utilizing Convolutional Neural Network Based Optical Coherence Tomography Image Classification Method

      Background The purpose of this study was to develop a deep learning classification approach to distinguish cancerous from noncancerous regions within optical coherence tomography (OCT) images of breast tissue for potential use in an intraoperative setting for margin assessment. Methods A custom ultrahigh-resolution OCT (UHR-OCT) system with an axial resolution of 2.7 μm and a lateral resolution of 5.5 μm was used in this study. The algorithm used an A-scan-based classification scheme and the convolutional neural network (CNN) was implemented using an 11-layer architecture consisting of serial 3 × 3 convolution kernels. Four tissue types were classified, including adipose ...

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    7. Chip-based frequency comb sources for optical coherence tomography

      Chip-based frequency comb sources for optical coherence tomography

      Optical coherence tomography (OCT) is a powerful interferometric imaging technique widely used in medical fields such as ophthalmology, cardiology and dermatology. Superluminescent diodes (SLDs) are widely used as light sources in OCT. Recently integrated chip-based frequency combs have been demonstrated in numerous platforms and the possibility of using these broadband chip-scale combs for OCT has been raised extensively over the past few years. However, the use of these chip-based frequency combs as light sources for OCT requires bandwidth and power compatibility with current OCT systems and have not been shown to date. Here we generate frequency combs based on chip-scale ...

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    8. Optical coherence tomography imaging of cardiac substrates

      Optical coherence tomography imaging of cardiac substrates

      Cardiovascular disease is the leading cause of morbidity and mortality in the United States. Knowledge of a patient’s heart structure will help to plan procedures, potentially identifying arrhythmia substrates, critical structures to avoid, detect transplant rejection, and reduce ambiguity when interpreting electrograms and functional measurements. Similarly, basic research of numerous cardiac diseases would greatly benefit from structural imaging at cellular scale. For both applications imaging on the scale of a myocyte is needed, which is approximately 100 µm × 10 µm. The use of optical coherence tomography (OCT) as a tool for characterizing cardiac tissue structure and function has been ...

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    9. Chip-based frequency combs sources for optical coherence tomography

      Chip-based frequency combs sources for optical coherence tomography

      The Optical coherence tomography (OCT) is a powerful interferometric imaging technique widely used in medical fields such as ophthalmology, cardiology and dermatology, for which footprint and cost are becoming increasingly important. Here we present a platform for miniaturized sources for OCT based on chip-scale lithographically defined microresonators. We show that the proposed platform is compatible with standard commercial spectral domain (SD) OCT systems and enable imaging of human tissue with an image quality comparable to the one achieved with tabletop commercial sources. This platform provides a path towards fully integrated OCT systems

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    10. Ultrahigh resolution spectral domain optical coherence tomography and its functional extension for human myocardium and breast tissue imaging (Thesis)

      Ultrahigh resolution spectral domain optical coherence tomography and its functional extension for human myocardium and breast tissue imaging (Thesis)

      Over the past 25 years of development and innovation, optical coherence tomography (OCT) has successfully fills the gap between the ex vivo high-resolution optical microscopy technologies and in vivo low-resolution medical imaging modalities, including computed tomography (CT), magnetic resonance imaging (MRI), ultrasound (US). Ultrahigh resolution (UHR) OCT categorizes OCT systems with an axial resolution below 3 µm in tissue. With the improved resolution, UHR OCT may impart the knowledge of detailed structures of the tissues that are almost close to what histology may provide. This is how UHR OCT can act as a bridge between radiology and histology. This thesis ...

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    11. Multi-contrast Endomyocardial Imaging By Single-channel High Resolution Cross-polarization Optical Coherence Tomography

      Multi-contrast Endomyocardial Imaging By Single-channel High Resolution Cross-polarization Optical Coherence Tomography

      A single-channel high-resolution cross-polarization (CP) optical coherence tomography (OCT) system is presented for multi-contrast imaging of human myocardium in one-shot measurement. The intensity contrast and functional contrasts, including the ratio between the cross- and co- polarization channels as well as the cumulative retardation, are reconstructed from the CP-OCT readout. By comparing the CP-OCT results with histological analysis, it is shown that the system can successfully delineate micro-structures in the myocardium and differentiate the fibrotic myocardium from normal or ablated myocardium based the functional contrasts provided by the CP-OCT system. The feasibility of using A-line profiles from the two orthogonal polarization ...

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    12. Highly phase-stable 200 kHz swept-source optical coherence tomography based on KTN electro-optic deflector

      Highly phase-stable 200 kHz swept-source optical coherence tomography based on KTN electro-optic deflector

      The rapid advance in swept-source optical coherence tomography (SS-OCT) technology has enabled exciting new applications in elastography, angiography, and vibrometry, where both high temporal resolution and phase stability are highly sought-after. In this paper, we present a 200 kHz SS-OCT system centered at 1321 nm by using an electro-optically tuned swept source. The proposed system’s performance was fully characterized, and it possesses superior phase stability (0.0012% scanning variability and <1 ns timing jitter) that is promising for many phase-sensitive imaging applications. Biological experiments were demonstrated within ex vivo human tracheobronchial ciliated epithelium where both the ciliary motion and ...

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    13. Highly phase-stable 200 kHz swept-source optical coherence tomography based on KTN electro-optic deflector

      Highly phase-stable 200 kHz swept-source optical coherence tomography based on KTN electro-optic deflector

      The rapid advance in swept-source optical coherence tomography (SS-OCT) technology has enabled exciting new applications in elastography, angiography, and vibrometry, where both high temporal resolution and phase stability are highly sought-after. In this paper, we present a 200 kHz SS-OCT system centered at 1321 nm by using an electro-optically tuned swept source. The proposed system’s performance was fully characterized, and it possesses superior phase stability (0.0012% scanning variability and <1 ns timing jitter) that is promising for many phase-sensitive imaging applications. Biological experiments were demonstrated within ex vivo human tracheobronchial ciliated epithelium where both the ciliary motion and ...

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    14. Phase-noise analysis of swept-source optical coherence tomography systems

      Phase-noise analysis of swept-source optical coherence tomography systems

      We propose a new model to characterize the phase noise in swept-source optical coherence tomography (SS-OCT). The new model explicitly incorporates scanning variability, timing jitter, and sample location in addition to intensity noise (shot noise). The model was analyzed and validated by using both Monte Carlo methods and experiments. We suggest that the proposed model can be used as a guideline for future SS-OCT experimental designs.

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    15. Feature Of The Week 03/12/2017: Visualization and tissue classification of human breast cancer images using ultrahigh-resolution OCT

      Feature Of The Week 03/12/2017: Visualization and tissue classification of human breast cancer images using ultrahigh-resolution OCT

      Breast cancer is one of the leading cause of mortality in women. Optical coherence tomography (OCT) enables three dimensional visualization of biological tissue with micrometer level resolution at high speed, and can play an important role in early diagnosis and treatment guidance of breast cancer. In this study, we imaged human breast tissue using two spectral domain OCT systems at different wavelengths: a home-built ultra-high resolution (UHR) OCT system at 840nm (measured as 2.72 µm axial and 5.52 µm lateral) and a commercial OCT system at 1300nm with standard resolution (measured as 6.5 µm axial and 15 ...

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    16. Visualization and tissue classification of human breast cancer images using ultrahigh-resolution OCT

      Visualization and tissue classification of human breast cancer images using ultrahigh-resolution OCT

      Background and Objective Breast cancer is one of the most common cancers, and recognized as the third leading cause of mortality in women. Optical coherence tomography (OCT) enables three dimensional visualization of biological tissue with micrometer level resolution at high speed, and can play an important role in early diagnosis and treatment guidance of breast cancer. In particular, ultra-high resolution (UHR) OCT provides images with better histological correlation. This paper compared UHR OCT performance with standard OCT in breast cancer imaging qualitatively and quantitatively. Automatic tissue classification algorithms were used to automatically detect invasive ductal carcinoma in ex vivo human ...

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    17. Automated fiber tracking and tissue characterization of the anterior cruciate ligament with optical coherence tomography

      Automated fiber tracking and tissue characterization of the anterior cruciate ligament with optical coherence tomography

      The directionality of collagen fibers across the anterior cruciate ligament (ACL) as well as the insertion of this key ligament into bone are important for understanding the mechanical integrity and functionality of this complex tissue. Quantitative analysis of three-dimensional fiber directionality is of particular interest due to the physiological, mechanical, and biological heterogeneity inherent across the ACL-to-bone junction, the behavior of the ligament under mechanical stress, and the usefulness of this information in designing tissue engineered grafts. We have developed an algorithm to characterize Optical Coherence Tomography (OCT) image volumes of the ACL. We present an automated algorithm for measuring ...

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    18. Ex vivo visualization of human ciliated epithelium and quantitative analysis of induced flow dynamics by using optical coherence tomography

      Ex vivo visualization of human ciliated epithelium and quantitative analysis of induced flow dynamics by using optical coherence tomography

      Background and Objective Cilia-driven mucociliary clearance is an important self-defense mechanism of great clinical importance in pulmonary research. Conventional light microscopy possesses the capability to visualize individual cilia and its beating pattern but lacks the throughput to assess the global ciliary activities and flow dynamics. Optical coherence tomography (OCT), which provides depth-resolved cross-sectional images, was recently introduced to this area. Materials and Methods Fourteen de-identified human tracheobronchial tissues are directly imaged by two OCT systems: one system centered at 1,300 nm with 6.5 μm axial resolution and 15 μm lateral resolution, and the other centered at 800 nm ...

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    19. Characterization of ventricular endomyocardial tissue using optical coherence tomography

      Characterization of ventricular endomyocardial tissue using optical coherence tomography

      We present an initial study to describe the potential of optical coherence tomography (OCT) for characterizing endomyocardial tissue. We obtained ventricular OCT images from 15 fresh human hearts. Layer thickness measurements and texture features were extracted from volumetric datasets with endocardial thickening, normal myocardium, myocardium with interstitial fibrosis, normal endocardium, and adipose tissue. Within our datasets, we observed that the thickness of endocardium was not different within samples with normal or myocardium with interstitial fibrosis, however samples with endocardial thickening showed statistically increased endocardial thickness.

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    20. Myocardial imaging using ultrahigh-resolution spectral domain optical coherence tomography

      Myocardial imaging using ultrahigh-resolution spectral domain optical coherence tomography

      We present an ultrahigh-resolution spectral domain optical coherence tomography (OCT) system in 800 nm with a low-noise supercontinuum source (SC) optimized for myocardial imaging. The system was demonstrated to have an axial resolution of 2.72 μm  with a large imaging depth of 1.78 mm and a 6-dB falloff range of 0.89 mm. The lateral resolution ( 5.52  μm ) was compromised to enhance the image penetration required for myocardial imaging. The noise of the SC source was analyzed extensively and an imaging protocol was proposed for SC-based OCT imaging with appreciable contrast. Three-dimensional datasets were acquired ex vivo ...

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    1-20 of 20
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  2. Topics in the News

    1. (17 articles) Columbia University
    2. (17 articles) Christine P. Hendon
    3. (3 articles) Singapore Eye Research Institute
    4. (2 articles) University of Alabama
    5. (2 articles) Cornell University
    6. (2 articles) Topcon Medical Systems
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    12. (1 articles) Tohoku University
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    Myocardial imaging using ultrahigh-resolution spectral domain optical coherence tomography Characterization of ventricular endomyocardial tissue using optical coherence tomography Ex vivo visualization of human ciliated epithelium and quantitative analysis of induced flow dynamics by using optical coherence tomography Visualization and tissue classification of human breast cancer images using ultrahigh-resolution OCT Feature Of The Week 03/12/2017: Visualization and tissue classification of human breast cancer images using ultrahigh-resolution OCT Phase-noise analysis of swept-source optical coherence tomography systems Highly phase-stable 200 kHz swept-source optical coherence tomography based on KTN electro-optic deflector Multi-contrast Endomyocardial Imaging By Single-channel High Resolution Cross-polarization Optical Coherence Tomography Ultrahigh resolution spectral domain optical coherence tomography and its functional extension for human myocardium and breast tissue imaging (Thesis) Beyond Fourier transform: break the axial resolution limit in optical coherence tomography Spectral Domain Optical Coherence Tomography Imaging Performance Improvement Based on Field Curvature Aberration-Corrected Spectrometer Pentosan polysulfate maculopathy versus inherited macular dystrophies: comparative assessment with multimodal imaging