1. Articles from Jiang Zhu

    1-24 of 27 1 2 »
    1. Improving cerebral microvascular image quality of optical coherence tomography angiography with deep learning-based segmentation

      Improving cerebral microvascular image quality of optical coherence tomography angiography with deep learning-based segmentation

      Optical coherence tomography angiography (OCTA) can map the microvascular networks of the cerebral cortices with micrometer resolution and millimeter penetration. However, the high scattering of the skull and the strong noise in the deep imaging region will distort the vasculature projections and decrease the OCTA image quality. Here, we proposed a deep learning-based segmentation method based on a U-Net convolutional neural network to extract the cortical region from the OCT image. The vascular networks were then visualized by three OCTA algorithms. The image quality of the vasculature projections was assessed by two metrics, including the peak signal-to-noise ratio (PSNR) and ...

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    2. Characterizing Rayleigh wave and longitudinal shear wave propagation for measurements of elastic moduli using optical coherence elastography

      Characterizing Rayleigh wave and longitudinal shear wave propagation for measurements of elastic moduli using optical coherence elastography

      Optical coherence elastography based on the measurements of elastic wave speeds can quantify elastic moduli in the wave propagation directions and provide high-resolution elasticity maps for tissue. Here, we simultaneously visualized a longitudinal shear wave propagating along the depth and a Rayleigh wave propagating in the lateral direction, and analyzed the propagation characteristics of the elastic waves, including group speeds, frequency spectra, and frequency-dependent wave speeds. The analysis of the propagation characteristics demonstrates the reliability of the elasticity quantification by measuring different types of speeds of the elastic waves.

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    3. Optical Coherence Tomography Angiography for Mapping Cerebral Microvasculature Based on Normalized Differentiation Analysis

      Optical Coherence Tomography Angiography for Mapping Cerebral Microvasculature Based on Normalized Differentiation Analysis

      Optical coherence tomography angiography (OCTA) is a label‐free, noninvasive biomedical imaging modality for mapping microvascular networks and quantifying blood flow velocities in vivo . Simple computation and fast processing are critical for the OCTA in some applications. Herein, we report on a normalized differentiation method for mapping cerebral microvasculature with the advantages of simple analysis and high image quality, benefitting from computation of differentiation and characteristics of normalization. Normalized differentiation values are validated to have a nearly linear relationship with flow velocities in a range using a flow phantom. The measurements in a rat cerebral cortex show that the OCTA ...

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    4. Quantitative Assessment of Optical Coherence Tomography Angiography Algorithms for Neuroimaging

      Quantitative Assessment of Optical Coherence Tomography Angiography Algorithms for Neuroimaging

      Optical coherence tomography (OCT) angiography can noninvasively map microvascular networks and quantify blood flow in a cerebral cortex with a resolution of 1–10 μm and a penetration depth of 2–3 mm incorporating OCT signals and angiography algorithms. Different angiography algorithms have been developed in recent years; however, the performance of the algorithms has not been assessed quantitatively for neuroimaging applications. In this paper, we developed four metrics including vascular connectivity, contrast‐to‐noise ratio (CNR), signal‐to‐noise ratio (SNR) and processing time to quantitatively assess the performance of OCT angiography algorithms in image quality and computation speed ...

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    5. Optical Vaginal Biopsy Using Optical Coherence Tomography

      Optical Vaginal Biopsy Using Optical Coherence Tomography

      Objective Optical coherence tomography is a noninvasive technology that visualizes tissue microstructure with high spatial resolution. We designed a novel vaginal system that demonstrates a clear distinction between vaginal tissues planes. In this study, we sought to compare vaginal tomographic images of premenopausal, perimenopausal, and postmenopausal women, demonstrate feasibility of tracking vaginal tissue changes after treatment with fractional-pixel CO 2 laser therapy, and obtain a histologic correlation of these findings. Methods Enrolled subjects underwent imaging and were divided into 3 groups based on menopausal status. Women with genitourinary syndrome of menopause who received fractional-pixel CO 2 laser therapy were assessed ...

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      Mentions: UC Irvine
    6. Extended imaging depth of en-face optical coherence tomography based on fast measurement of a reflection matrix by wide-field heterodyne detection

      Extended imaging depth of en-face optical coherence tomography based on fast measurement of a reflection matrix by wide-field heterodyne detection

      Multiple light scattering in biomedical tissue limits the penetration depth of optical imaging systems such as optical coherence tomography. To increase the imaging depth in scattering media, a computational method based on coherent reflection matrix measurement has been developed using low coherence interferometry. The complex reflection matrix is obtained via point-by-point scanning followed by a phase-shifting method; then singular value decomposition is used to retrieve the singly back-scattered light. However, the in vivo application of the current reported method is limited due to the slow acquisition speed of the matrix. In this Letter, a wide-field heterodyne-detection method is adopted to ...

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      Mentions: UC Irvine
    7. Spatiotemporal dynamics of pial collateral blood flow following permanent middle cerebral artery occlusion in a rat model of sensory-based protection: a Doppler optical coherence tomography study

      Spatiotemporal dynamics of pial collateral blood flow following permanent middle cerebral artery occlusion in a rat model of sensory-based protection: a Doppler optical coherence tomography study

      There is a growing recognition regarding the importance of pial collateral flow in the protection from impending ischemic stroke both in preclinical and clinical studies. Collateral flow is also a major player in sensory stimulation-based protection from impending ischemic stroke. Doppler optical coherence tomography has been employed to image spatiotemporal patterns of collateral flow within the dorsal branches of the middle cerebral artery (MCA) as it provides a powerful tool for quantitative in vivo flow parameters imaging (velocity, flux, direction of flow, and radius of imaged branches). It was employed prior to and following dorsal permanent MCA occlusion (pMCAo) in ...

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      Mentions: UC Irvine
    8. Assessment of blood coagulation using an acoustic radiation force based optical coherence elastography (ARF-OCE)

      Assessment of blood coagulation using an acoustic radiation force based optical coherence elastography (ARF-OCE)

      An apparatus and method of using an optical coherence elastography (OCE) under acoustic radiation force (ARF) excitation includes the steps of inducing an excitation wave in a blood sample by use of an ultrasound beam from an ultrasonic transducer; measuring an elastic property of the blood sample by use of an optical coherence tomography (OCT) beam transverse to the ultrasound beam to dynamically measure the elastic property of the blood sample during coagulation and assessing the clot formation/dissolution kinetics and strength.

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      Mentions: UC Irvine
    9. Perspective: Current challenges and solutions of Doppler optical coherence tomography and angiography for neuroimaging

      Perspective: Current challenges and solutions of Doppler optical coherence tomography and angiography for neuroimaging

      The nervous system, based on a complex network of nerves and cells, carries messages by transmitting signals to and from different parts of the body. The supply of blood flow in the nervous system is critical to maintain physiological functions. Optical coherence tomography (OCT) has the ability to noninvasively image the microvascular networks and accurately quantify the blood flow in vivo with high spatial and temporal resolutions in three dimensions. It has been used to measure changes in blood supplies and assess physiological functions before and after occurrences of diseases, drug administration, and external stimulation in the nervous system, especially ...

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      Mentions: UC Irvine
    10. 1.7 micron optical coherence tomography for vaginal tissue characterization in vivo

      1.7 micron optical coherence tomography for vaginal tissue characterization in vivo

      Objectives Optical coherence tomography (OCT) can noninvasively visualize in vivo tissue microstructure with high spatial resolution that approaches the histologic level. Currently, OCT studies in gynecology are few and limited to a conventional 1.3 μm center wavelength swept light source which provides high spatial resolution but limited penetration depth. Here, we present a novel endoscopic OCT system with improved penetration depth and high resolution. Methods A novel endoscopic OCT system was developed based on a 1.7 µm swept source laser, which is capable of deeper tissue penetration due to its longer wavelength. To evaluate the performance of system ...

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      Mentions: UC Irvine
    11. Deep imaging in highly scattering media by combining reflection matrix measurement with Bessel-like beam based optical coherence tomography

      Deep imaging in highly scattering media by combining reflection matrix measurement with Bessel-like beam based optical coherence tomography

      Multiple scattering in biomedical tissue limits the imaging depth within a range of 1–2 mm for conventional optical imaging techniques. To extend the imaging depth into the scattering medium, a computational method based on the reflection matrix measurement has been developed to retrieve the singly back-scattered signal light from the dominant detrimental multiple-scattered background. After applying singular value decomposition on the measured matrix in the post-process, the target image underneath the turbid media is clearly recovered. To increase the depth of focus of the incident light by elongating the focal spot along the optical axis, a digital grating pattern ...

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      Mentions: UC Irvine
    12. Viscosity monitoring during hemodiluted blood coagulation using optical coherence elastography

      Viscosity monitoring during hemodiluted blood coagulation using optical coherence elastography

      Rapid and accurate clot diagnostic systems are needed for the assessment of hemodiluted blood coagulation. We develop a real-time optical coherence elastography (OCE) system, which measures the attenuation coefficient of a compressional wave induced by a piezoelectric transducer (PZT) in a drop of blood using optical coherence tomography (OCT), for the determination of viscous properties during the dynamic whole blood coagulation process. Changes in the viscous properties increase the attenuation coefficient of the sample. Consequently, dynamic blood coagulation status can be monitored by relating changes of the attenuation coefficient to clinically relevant coagulation metrics, including the initial coagulation time and ...

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    13. Quantitative angle-insensitive flow measurement using relative standard deviation OCT

      Quantitative angle-insensitive flow measurement using relative standard deviation OCT

      Incorporating different data processing methods, optical coherence tomography (OCT) has the ability for high-resolution angiography and quantitative flow velocity measurements. However, OCT angiography cannot provide quantitative information of flow velocities, and the velocity measurement based on Doppler OCT requires the determination of Doppler angles, which is a challenge in a complex vascular network. In this study, we report on a relative standard deviation OCT (RSD-OCT) method which provides both vascular network mapping and quantitative information for flow velocities within a wide range of Doppler angles. The RSD values are angle-insensitive within a wide range of angles, and a nearly linear ...

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      Mentions: UC Irvine
    14. Intravascular Optical Coherence Tomography for Characterization of Atherosclerosis with a 1.7 Micron Swept-Source Laser

      Intravascular Optical Coherence Tomography for Characterization of Atherosclerosis with a 1.7 Micron Swept-Source Laser

      The main cause of acute coronary events, such as thrombosis, is the rupture of atherosclerotic plaques. Typical intravascular optical coherence tomography (IVOCT) imaging systems that utilize a 1.3 μm swept source laser are often used for identifying fibrous cap thickness of plaques, yet cannot provide adequate depth penetration to resolve the size of the lipid pool. Here, we present a novel IVOCT system with a 1.7 μm center wavelength swept light source that can readily penetrate deeper into the tissue because of the longer wavelength and allows for better identification of plaques due to the lipid absorption spectrum ...

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      Mentions: UC Irvine
    15. 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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    16. Feature of The Week 05/19/2017: Longitudinal Shear Wave Imaging for Elasticity Mapping Using Optical Coherence Elastography

      Feature of The Week 05/19/2017: Longitudinal Shear Wave Imaging for Elasticity Mapping Using Optical Coherence Elastography

      Shear wave measurements for the determination of tissue elastic properties have been used in clinical diagnosis and soft tissue assessment. A shear wave propagates as a transverse wave where vibration is perpendicular to the wave propagation direction. Using shear wave elastography, the shear modulus of a soft tissue can be quantified by tracking the shear wave propagation. In previous measurements, the transverse shear wave propagates perpendicular to the force direction, so the shear modulus in the lateral region of the force can be quantified. However, the shear modulus in the axial region of the force cannot be measured. Dr. Jiang ...

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      Mentions: UC Irvine
    17. Longitudinal shear wave imaging for elasticity mapping using optical coherence elastography

      Longitudinal shear wave imaging for elasticity mapping using optical coherence elastography

      Shear wave measurements for the determination of tissue elastic properties have been used in clinical diagnosis and soft tissue assessment. A shear wave propagates as a transverse wave where vibration is perpendicular to the wave propagation direction. Previous transverse shear wave measurements could detect the shear modulus in the lateral region of the force; however, they could not provide the elastic information in the axial region of the force. In this study, we report the imaging and quantification of longitudinal shear wave propagation using optical coherence tomography to measure the elastic properties along the force direction. The experimental validation and ...

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      Mentions: UC Irvine
    18. Coagulation monitoring based on blood elastic measurement using optical coherence tomography

      Coagulation monitoring based on blood elastic measurement using optical coherence tomography

      Blood coagulation monitoring is important to diagnose hematological diseases and cardiovascular diseases and to predict the risk of bleeding and excessive clotting. In this study, we developed a system to dynamically monitor blood coagulation and quantitatively determine the coagulation function by blood elastic measurement. When blood forms a clot from a liquid, ultrasonic force induces a shear wave, which is detected by optical coherence tomography (OCT). The coagulation of porcine whole blood recalcified by calcium chloride is assessed using the metrics of reaction time, clot formation kinetics and maximum shear modulus. The OCE system can noninvasively monitor the blood coagulation ...

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    19. 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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      Mentions: UC Irvine
    20. 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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      Mentions: UC Irvine
    21. 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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      Mentions: UC Irvine
    22. Dynamic and quantitative assessment of blood coagulation using optical coherence elastography

      Dynamic and quantitative assessment of blood coagulation using optical coherence elastography

      Reliable clot diagnostic systems are needed for directing treatment in a broad spectrum of cardiovascular diseases and coagulopathy. Here, we report on non-contact measurement of elastic modulus for dynamic and quantitative assessment of whole blood coagulation using acoustic radiation force orthogonal excitation optical coherence elastography (ARFOE-OCE). In this system, acoustic radiation force (ARF) is produced by a remote ultrasonic transducer, and a shear wave induced by ARF excitation is detected by the optical coherence tomography (OCT) system. During porcine whole blood coagulation, changes in the elastic property of the clots increase the shear modulus of the sample, altering the propagating ...

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      Mentions: UC Irvine
    23. Automatic three-dimensional segmentation combined with in vivo microvascular network imaging of human retina by intensity-based Doppler variance optical coherence tomography

      Automatic three-dimensional segmentation combined with in vivo microvascular network imaging of human retina by intensity-based Doppler variance optical coherence tomography

      Optical coherence tomography (OCT) is a noninvasive method for retinal imaging. In this work, we present an in vivo human retinal microvascular network measurement by an intensity-based Doppler variance (IBDV) based on sweptsource OCT. In addition, an automatic three-dimensional (3-D) segmentation method was used for segmenting intraretinal layers. The microvascular networks were divided into six layers by visualizing of each individual layer with enhanced imaging contrast. This method has potential for earlier diagnosis and precise monitoring in retinal vascular diseases.

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    24. 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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      Mentions: UC Irvine
    1-24 of 27 1 2 »
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    Automatic airway wall segmentation and thickness measurement for long-range optical coherence tomography images Fully distributed absolute blood flow velocity measurement for middle cerebral arteries using Doppler optical coherence tomography Automatic three-dimensional segmentation combined with in vivo microvascular network imaging of human retina by intensity-based Doppler variance optical coherence tomography Coagulation monitoring based on blood elastic measurement using optical coherence tomography Longitudinal shear wave imaging for elasticity mapping using optical coherence elastography Feature of The Week 05/19/2017: Longitudinal Shear Wave Imaging for Elasticity Mapping Using Optical Coherence Elastography Miniature probe for mapping mechanical properties of vascular lesions using acoustic radiation force optical coherence elastography Intravascular Optical Coherence Tomography for Characterization of Atherosclerosis with a 1.7 Micron Swept-Source Laser 1.7 micron optical coherence tomography for vaginal tissue characterization in vivo Perspective: Current challenges and solutions of Doppler optical coherence tomography and angiography for neuroimaging Investigation of Light Parameters on Image Quality and Optical Coherence Tomography Potential Utility of Adjunct Imaging with Wide-Field Optical Coherence Tomography for Gross and Microscopic Evaluation of Breast Specimens in Real-Time in the Operating Suite