1. Articles from Chen Wu

    1-24 of 31 1 2 »
    1. Optical coherence elastography of cold cataract in porcine lens

      Optical coherence elastography of cold cataract in porcine lens

      Cataract is one of the most prevalent causes of blindness around the world. Understanding the mechanisms of cataract development and progression is important for clinical diagnosis and treatment. Cold cataract has proven to be a robust model for cataract formation that can be easily controlled in the laboratory. There is evidence that the biomechanical properties of the lens can be significantly changed by cataract. Therefore, early detection of cataract, as well as evaluation of therapies, could be guided by characterization of lenticular biomechanical properties. In this work, we utilized optical coherence elastography (OCE) to monitor the changes in biomechanical properties ...

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    2. Assessing the biomechanical properties of the porcine crystalline lens as a function of intraocular pressure with optical coherence elastography

      Assessing the biomechanical properties of the porcine crystalline lens as a function of intraocular pressure with optical coherence elastography

      In this study, we investigated the relationship between the biomechanical properties of the crystalline lens and intraocular pressure (IOP) using a confocal acoustic radiation force (ARF) and phase-sensitive optical coherence elastography (OCE) system. ARF induced a small displacement at the apex of porcine lenses in situ at various artificially controlled IOPs. Maximum displacement, relaxation rate, and Young’s modulus were utilized to assess the stiffness of the crystalline lens. The results showed that the stiffness of the crystalline increased as IOP increased, but the lens stiffening was not as significant as the stiffening of other ocular tissues such as the ...

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    3. Quantifying changes in lens biomechanical properties due to cold cataract with optical coherence elastography

      Quantifying changes in lens biomechanical properties due to cold cataract with optical coherence elastography

      Cataract is the most prevalent cause of visual impairment worldwide. Cataracts can be formed due to trauma, radiation, drug abuse, or low temperatures. Thus, early detection of cataract can be immensely helpful for preserving visual acuity by ensuring that the appropriate therapeutic procedures are performed at earlier stages of disease onset and progression. In this work, we utilized a phase-sensitive optical coherence elastography (OCE) system to quantify changes in biomechanical properties of porcine lenses in vitro with induced cold cataracts. The results show significant increase in lens Young’s modulus due to formation of the cold cataract (from ~ 35 kPa ...

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    4. Evaluating the Effects of Maternal Alcohol Consumption on Murine Fetal Brain Vasculature Using Optical Coherence Tomography

      Evaluating the Effects of Maternal Alcohol Consumption on Murine Fetal Brain Vasculature Using Optical Coherence Tomography

      Prenatal alcohol exposure (PAE) can result in a range of anomalies including brain and behavioral dysfunctions, collectively termed fetal alcohol spectrum disorder (FASD). PAE during the 1 st and 2 nd trimester is common, and research in animal models has documented significant neural developmental deficits associated with PAE during this period. However, little is known about the immediate effects of PAE on fetal brain vasculature. In this study, we used in utero speckle variance optical coherence tomography (SVOCT), a high spatial- and temporal–resolution imaging modality, to evaluate dynamic changes in micro-vasculature of the 2 nd trimester-equivalent murine fetal brain ...

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    5. Comparison and combination of rotational imaging optical coherence tomography and selective plane illumination microscopy for embryonic study

      Comparison and combination of rotational imaging optical coherence tomography and selective plane illumination microscopy for embryonic study

      Several optical imaging techniques have been applied for high-resolution embryonic imaging using different contrast mechanisms, each with their own benefits and limitations. In this study, we imaged the same E9.5 mouse embryo with rotational imaging optical coherence tomography (RI-OCT) and selective plane illumination microscopy (SPIM). RI-OCT overcomes optical penetration limits of traditional OCT imaging that prohibit full-body imaging of mouse embryos at later stages by imaging the samples from multiple angles. SPIM enables high-resolution, 3D imaging with less phototoxicity and photobleaching than laser scanning confocal microscopy (LSCM) by illuminating the sample with a focused sheet of light. Side by ...

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    6. Evaluating biomechanical properties of murine embryos using Brillouin microscopy and optical coherence tomography

      Evaluating biomechanical properties of murine embryos using Brillouin microscopy and optical coherence tomography

      Embryogenesis is regulated by numerous changes in mechanical properties of the cellular microenvironment. Thus, studying embryonic mechanophysiology can provide a more thorough perspective of embryonic development, potentially improving early detection of congenital abnormalities as well as evaluating and developing therapeutic interventions. A number of methods and techniques have been used to study cellular biomechanical properties during embryogenesis. While some of these techniques are invasive or involve the use of external agents, others are compromised in terms of spatial and temporal resolutions. We propose the use of Brillouin microscopy in combination with optical coherence tomography (OCT) to measure stiffness as well ...

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    7. Optical coherence elastography to assess biomechanics and detect progression of ocular and other tissues degenerative diseases

      Optical coherence elastography to assess biomechanics and detect progression of ocular and other tissues degenerative diseases

      An excitation force (internal or external) and phase-sensitive optical coherence elastography (OCE) system, used in conjunction with a data analyzing algorithm, is capable of measuring and quantifying biomechanical parameters of tissues in situ and in vivo. The method was approbated and demonstrated on an example of the system that combines a pulsed ultrasound system capable of producing an acoustic radiation force on the crystalline lens surface and a phase-sensitive optical coherence tomography (OCT) system for measuring the lens displacement caused by the acoustic radiation force. The method allows noninvasive and nondestructive quantification of tissue mechanical properties. The noninvasive measurement method ...

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    8. A dual-modality optical coherence tomography and selective plane illumination microscopy system for mouse embryonic imaging

      A dual-modality optical coherence tomography and selective plane illumination microscopy system for mouse embryonic imaging

      Both optical coherence tomography (OCT) and selective plane illumination microscopy (SPIM) are frequently used in mouse embryonic research for high-resolution three-dimensional imaging. However, each of these imaging methods provide a unique and independent advantage: SPIM provides morpho-functional information through immunofluorescence and OCT provides a method for whole-embryo 3D imaging. In this study, we have combined rotational imaging OCT and SPIM into a single, dual-modality device to image E9.5 mouse embryos. The results demonstrate that the dual-modality setup is able to provide both anatomical and functional information simultaneously for more comprehensive tissue characterization

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    9. Ultra-fast line-field low coherence holographic elastography using spatial phase shifting

      Ultra-fast line-field low coherence holographic elastography using spatial phase shifting

      Optical coherence elastography (OCE) is an emerging technique for quantifying tissue biomechanical properties. Generally, OCE relies on point-by-point scanning. However, long acquisition times make point-by-point scanning unfeasible for clinical use. Here we demonstrate a noncontact single shot line-field low coherence holography system utilizing an automatic Hilbert transform analysis based on a spatial phase shifting technique. Spatio-temporal maps of elastic wave propagation were acquired with only one air-pulse excitation and used to quantify wave velocity and sample mechanical properties at a line rate of 200 kHz. Results obtained on phantoms were correlated with data from mechanical testing. Finally, the stiffness of ...

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    10. Assessing the effects of riboflavin/UV-A crosslinking on porcine corneal mechanical anisotropy with optical coherence elastography

      Assessing the effects of riboflavin/UV-A crosslinking on porcine corneal mechanical anisotropy with optical coherence elastography

      In this work we utilize optical coherence elastography (OCE) to assess the effects of UV-A/riboflavin corneal collagen crosslinking (CXL) on the mechanical anisotropy of in situ porcine corneas at various intraocular pressures (IOP). There was a distinct meridian of increased Young’s modulus in all samples, and the mechanical anisotropy increased as a function of IOP and also after CXL. The presented noncontact OCE technique was able to quantify the Young’s modulus and elastic anisotropy of the cornea and their changes as a function of IOP and CXL, opening new avenues of research for evaluating the effects of ...

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    11. Optical Modalities for Embryonic Imaging

      Optical Modalities for Embryonic Imaging

      tudies of disease etiology often rely on the murine (mouse) model, which provides valuable genotypic information. Yet associated phenotypic information from murine embryos is often lacking. Of the various techniques that have been proposed for imaging such embryos, optical modalities may provide the best compromise among speed, penetration depth and resolution. This year, we developed approaches to improve embryonic imaging with optical coherence tomography (OCT), 1 and also provided a detailed comparison of OCT and another modality, optical projection tomography (OPT), in murine-embryo studies. 2 Most commonly used for ophthalmological imaging, 3 OCT has proved a powerful embryonic-imaging modality as ...

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    12. Optical coherence elastography assessment of corneal viscoelasticity with a modified Rayleigh-Lamb wave model

      Optical coherence elastography assessment of corneal viscoelasticity with a modified Rayleigh-Lamb wave model

      The biomechanical properties of the cornea play a critical role in forming vision. Diseases such as keratoconus can structurally degenerate the cornea causing a pathological loss in visual acuity. UV-A/riboflavin corneal collagen crosslinking (CXL) is a clinically available treatment to stiffen the cornea and restore its healthy shape and function. However, current CXL techniques do not account for pre-existing biomechanical properties of the cornea nor the effects of the CXL treatment itself. In addition to the inherent corneal structure, the intraocular pressure (IOP) can also dramatically affect the measured biomechanical properties of the cornea. In this work, we present ...

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    13. Quantifying tissue viscoelasticity using optical coherence elastography and the Rayleigh wave model

      Quantifying tissue viscoelasticity using optical coherence elastography and the Rayleigh wave model

      This study demonstrates the feasibility of using the Rayleigh wave model (RWM) in combination with optical coherence elastography (OCE) technique to assess the viscoelasticity of soft tissues. Dispersion curves calculated from the spectral decomposition of OCE-measured air-pulse induced elastic waves were used to quantify the viscoelasticity of samples using the RWM. Validation studies were first conducted on 10% gelatin phantoms with different concentrations of oil. The results showed that the oil increased the viscosity of the gelatin phantom samples. This method was then used to quantify the viscoelasticity of chicken liver. The Young’s modulus of the chicken liver tissues ...

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    14. Investigating Elastic Anisotropy of the Porcine Cornea as a Function of Intraocular Pressure With Optical Coherence Elastography

      Investigating Elastic Anisotropy of the Porcine Cornea as a Function of Intraocular Pressure With Optical Coherence Elastography

      PURPOSE: To evaluate the elastic anisotropy of porcine corneas at different intraocular pressures (IOPs) using a noncontact optical coherence elastography (OCE) technique. METHODS: A focused air-pulse induced low amplitude (≤ 10 µ m) elastic waves in fresh porcine corneas (n = 7) in situ in the whole eye globe configuration. A home-built phase-stabilized swept source optical coherence elastography (PhS-SSOCE) system imaged the elastic wave propagation at different stepped radial directions. A closed-loop feedback system was used to artificially control the IOP and the OCE measurements were repeated as the IOP was incrementally increased from 15 to 30 mm Hg in 5-mm Hg increments ...

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    15. Evaluating the Effects of Riboflavin/UV-A and Rose-Bengal/Green Light Cross-Linking of the Rabbit Cornea by Noncontact Optical Coherence Elastography

      Evaluating the Effects of Riboflavin/UV-A and Rose-Bengal/Green Light Cross-Linking of the Rabbit Cornea by Noncontact Optical Coherence Elastography

      Purpose : The purpose of this study was to use noncontact optical coherence elastography (OCE) to evaluate and compare changes in biomechanical properties that occurred in rabbit cornea in situ after corneal collagen cross-linking by either of two techniques: ultraviolet-A (UV-A)/riboflavin or rose-Bengal/green light. Methods : Low-amplitude (≤10 μm) elastic waves were induced in mature rabbit corneas by a focused air pulse. Elastic wave propagation was imaged by a phase-stabilized swept source OCE (PhS-SSOCE) system. Corneas were then cross-linked by either of two methods: UV-A/riboflavin (UV-CXL) or rose-Bengal/green light (RGX). Phase velocities of the elastic waves were fitted ...

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    16. Applicability, usability, and limitations of murine embryonic imaging with optical coherence tomography and optical projection tomography

      Applicability, usability, and limitations of murine embryonic imaging with optical coherence tomography and optical projection tomography

      We present an analysis of imaging murine embryos at various embryonic developmental stages (embryonic day 9.5, 11.5, and 13.5) by optical coherence tomography (OCT) and optical projection tomography (OPT). We demonstrate that while OCT was capable of rapid high-resolution live 3D imaging, its limited penetration depth prevented visualization of deeper structures, particularly in later stage embryos. In contrast, OPT was able to image the whole embryos, but could not be used in vivo because the embryos must be fixed and cleared. Moreover, the fixation process significantly altered the embryo morphology, which was quantified by the volume of ...

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    17. Magnetic force Optical Coherence Elastography at 1.5 million a-lines per second

      Magnetic force Optical Coherence Elastography at 1.5 million a-lines per second

      Optical Coherence Elastography (OCE) has been widely used to characterize tissue elasticity. In this paper we introduce a new excitation method using magnetic force to induce shear waves in phantoms and tissues. The shear waves were imaged using an Optical Coherence Tomography system with an A-scan rate of ~1.5 million a-lines per second and the speed of the waves were used to quantify elasticity of different concentrations of agar sampled and porcine liver. The OCE results acquired from this magnetic force excitation were compared with the mechanical compressional tests for validation. The results showed that magnetic force OCE and ...

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    18. Combined optical coherence tomography and optical coherence elastography for glomerulonephritis classification

      Combined optical coherence tomography and optical coherence elastography for glomerulonephritis classification

      Acute Glomerulonephritis caused by anti-glomerular basement membrane disease has a high mortality due to delayed diagnosis. Thus, an accurate and early diagnosis is critical for preserving renal function. Currently, blood, urine, and tissue-based diagnoses can be time consuming, while ultrasound and CT imaging have relatively low spatial resolution. Optical coherence tomography (OCT) is a noninvasive imaging technique that provides superior spatial resolution (micron scale) as compared to ultrasound and CT. Pathological changes in tissue properties can be detected based on the optical metrics analyzed from the OCT signal, such as optical attenuation and speckle variance. Moreover, OCT does not rely ...

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    19. Comparison of rotational imaging optical coherence tomography and selective plane illumination microscopy for embryonic study

      Comparison of rotational imaging optical coherence tomography and selective plane illumination microscopy for embryonic study

      The mouse is a common model for studying developmental diseases. Different optical techniques have been developed to investigate mouse embryos, but each has its own set of limitations and restrictions. In this study, we imaged the same E9.5 mouse embryo with rotational imaging Optical Coherence Tomography (RI-OCT) and Selective Plane Illumination Microscopy (SPIM), and compared the two techniques. Results demonstrate that both methods can provide images with micrometer-scale spatial resolution. The RI-OCT technique was developed to increase imaging depth of OCT by performing traditional OCT imaging at multiple sides and co-registering the images. In SPIM, optical sectioning is achieved ...

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    20. A comparison study of Riboflavin/UV-A and Rose-Bengal/Green light cross-linking of the rabbit corneas using optical coherence elastography

      A comparison study of Riboflavin/UV-A and Rose-Bengal/Green light cross-linking of the rabbit corneas using optical coherence elastography

      The biomechanical properties of the cornea are critical factors which determine its health and subsequent visual acuity. Keratoconus is a structural degeneration of the cornea which can diminish vision quality. Riboflavin/UV-A corneal collagen cross-linking (UV-CXL) is an emerging treatment that increases the stiffness of the cornea and improves its ability to resist further degeneration. While UV-CXL has shown great promise for effective therapy of the keratoconus, there are concerns associated with the UV irradiation, such as keratocyte cytotoxicity. Rose-bengal/green light corneal collagen cross-linking (RGX) has been proposed as an alternative to UV-CXL. Because of the high absorbance of ...

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    21. Assessing the elasticity change of cataract lens with OCE

      Assessing the elasticity change of cataract lens with OCE

      Cataract is one of the most common degenerative diseases that causes blindness. Careful quantification of lens biomechanical properties can greatly assist in early detection of the disease as well as personalization of treatment procedures. In this study, we utilize a phase-sensitive optical coherence elastography (OCE) system to assess the effects of the cold cataract on the biomechanical properties of porcine crystalline lens in vitro. Relaxation rates of air puff induced elastic waves were measured on the same crystalline lens with and without cold cataract. Results demonstrate that the relaxation rate and, thus, associated elasticity of the porcine lens, increased due ...

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    22. Rotational imaging optical coherence tomography for full-body mouse embryonic imaging

      Rotational imaging optical coherence tomography for full-body mouse embryonic imaging

      Optical coherence tomography (OCT) has been widely used to study mammalian embryonic development with the advantages of high spatial and temporal resolutions and without the need for any contrast enhancement probes. However, the limited imaging depth of traditional OCT might prohibit visualization of the full embryonic body. To overcome this limitation, we have developed a new methodology to enhance the imaging range of OCT in embryonic day (E) 9.5 and 10.5 mouse embryos using rotational imaging. Rotational imaging OCT (RI-OCT) enables full-body imaging of mouse embryos by performing multiangle imaging. A series of postprocessing procedures was performed on ...

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    23. Classifying murine glomerulonephritis using optical coherence tomography and optical coherence elastography

      Classifying murine glomerulonephritis using optical coherence tomography and optical coherence elastography

      Elastic-wave propagation in mouse healthy and nephritic kidneys. Acute glomerulonephritis caused by antiglomerular basement membrane marked by high mortality. The primary reason for this is delayed diagnosis via blood examination, urine analysis, tissue biopsy, or ultrasound and X-ray computed tomography imaging. Blood, urine, and tissue-based diagnoses can be time consuming, while ultrasound and CT imaging have relatively low spatial resolution, with reduced sensitivity. Optical coherence tomography is a noninvasive and high-resolution imaging technique that provides superior spatial resolution (micrometer scale) as compared to ultrasound and CT. Changes in tissue properties can be detected based on the optical metrics analyzed from ...

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    24. Direct four-dimensional structural and functional imaging of cardiovascular dynamics in mouse embryos with 1.5  MHz optical coherence tomography

      Direct four-dimensional structural and functional imaging of cardiovascular dynamics in mouse embryos with 1.5  MHz optical coherence tomography

      High-resolution three-dimensional (3D) imaging of cardiovascular dynamics in mouse embryos is greatly desired to study mammalian congenital cardiac defects. Here, we demonstrate direct four-dimensional (4D) imaging of the cardiovascular structure and function in live mouse embryos at a ∼ 43     Hz volume rate using an optical coherence tomography (OCT) system with a ∼ 1.5     MHz Fourier domain mode-locking swept laser source. Combining ultrafast OCT imaging with live mouse embryo culture protocols, 3D volumes of the embryo are directly and continuously acquired over time for a cardiodynamics analysis without the application of any synchronization algorithms. We present the time-resolved measurements of the ...

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    1-24 of 31 1 2 »
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    Improvement of tissue analysis and classification using optical coherence tomography combined with Raman spectroscopy Assessing age-related changes in the biomechanical properties of rabbit lens using a co-aligned ultrasound and optical coherence elastography system Assessing Age-Related Changes in the Biomechanical Properties of Rabbit Lens Using a Coaligned Ultrasound and Optical Coherence Elastography System Elasticity measurement of nasal cartilage as a function of temperature using optical coherence elastography Feature Of The Week 03/22/15: Assessing Age-Related Changes in the Biomechanical Properties of Rabbit Lens using a Co-Focused Ultrasound and Optical Coherence Elastography System Direct four-dimensional structural and functional imaging of cardiovascular dynamics in mouse embryos with 1.5  MHz optical coherence tomography Classifying murine glomerulonephritis using optical coherence tomography and optical coherence elastography Combined optical coherence tomography and optical coherence elastography for glomerulonephritis classification Optical Modalities for Embryonic Imaging Evaluating biomechanical properties of murine embryos using Brillouin microscopy and optical coherence tomography Cascade Optical Coherence Tomography (C-OCT) for Surface Form Metrology of - ProQuest Comparison of Anterior Segment Measurements with a New Multifunctional Unit and Five Other Devices