1. Articles from Shi Gu

    1-16 of 16
    1. Phase-decorrelation optical coherence tomography-based parameter measurement

      Phase-decorrelation optical coherence tomography-based parameter measurement

      One example includes a scanning system. The system includes a phase-decorrelation optical coherence tomography (PhD-OCT) scanner configured to implement a scanning sequence via an optical signal on a sample medium. The system also includes a scanning controller configured to provide control signals to the PhD-OCT scanner to implement the scanning sequence and to obtain phase and amplitude information associated with a reflected version of the optical signal. The phase and amplitude information can be indicative of microscale dynamics of the sample medium. The scanning controller can also implement an algorithm to calculate a quantitative parameter of the sample medium based ...

      Read Full Article
    2. Noninvasive Assessment of Corneal Crosslinking With Phase-Decorrelation Optical Coherence Tomography

      Noninvasive Assessment of Corneal Crosslinking With Phase-Decorrelation Optical Coherence Tomography

      Purpose : There is strong evidence that abnormalities in corneal biomechanical play a causal role in corneal ectasias, such as keratoconus. Additionally, corneal crosslinking (CXL) treatment, which halts progression of keratoconus, directly appeals to corneal biomechanics. However, existing methods of corneal biomechanical assessment have various drawbacks: dependence on IOP, long acquisition times, or limited resolution. Here, we present a method that may avoid these limitations by using optical coherence tomography (OCT) to detect the endogenous random motion within the cornea, which can be associated with stromal crosslinking. Methods : Phase-decorrelation OCT (PhD-OCT), based in the theory of dynamic light scattering, is a ...

      Read Full Article
    3. Complex regression Doppler optical coherence tomography

      Complex regression Doppler optical coherence tomography

      We introduce a new method to measure Doppler shifts more accurately and extend the dynamic range of Doppler optical coherence tomography (OCT). The two-point estimate of the conventional Doppler method is replaced with a regression that is applied to high-density B-scans in polar coordinates. We built a high-speed OCT system using a 1.68-MHz Fourier domain mode locked laser to acquire high-density B-scans (16,000 A-lines) at high enough frame rates (∼100  fps) to accurately capture the dynamics of the beating embryonic heart. Flow phantom experiments confirm that the complex regression lowers the minimum detectable velocity from 12.25  mm ...

      Read Full Article
    4. Complex decorrelation averaging in optical coherence tomography: a way to reduce the effect of multiple scattering and improve image contrast in a dynamic scattering medium

      Complex decorrelation averaging in optical coherence tomography: a way to reduce the effect of multiple scattering and improve image contrast in a dynamic scattering medium

      We demonstrate that complex decorrelation averaging can reduce the effect of multiple scattering and improve optical coherence tomography (OCT) imaging contrast. Complex decorrelation averaging calculates the product of an A-scan and the complex conjugate of a subsequent A-scan. The resultant signal is the product of the amplitudes and the phase difference. All these resulting complex signals at a particular location are then averaged. We take advantage of the fact that complex averaging, in contrast to conventional magnitude averaging, is sensitive to phase decorrelation. Sample motion that increases signal phase variance results in lower signal magnitude after complex averaging. Such motion ...

      Read Full Article
    5. Mapping conduction velocity of early embryonic hearts with a robust fitting algorithm

      Mapping conduction velocity of early embryonic hearts with a robust fitting algorithm

      Cardiac conduction maturation is an important and integral component of heart development. Optical mapping with voltage-sensitive dyes allows sensitive measurements of electrophysiological signals over the entire heart. However, accurate measurements of conduction velocity during early cardiac development is typically hindered by low signal-to-noise ratio (SNR) measurements of action potentials. Here, we present a novel image processing approach based on least squares optimizations, which enables high-resolution, low-noise conduction velocity mapping of smaller tubular hearts. First, the action potential trace measured at each pixel is fit to a curve consisting of two cumulative normal distribution functions. Then, the activation time at each ...

      Read Full Article
    6. Feature Of The Week 02/22/15: Case Western Reserve University Demostrates Using OCT to Rapidly Phenotype and Quantify Congenital Heart Defects Associated with Prenatal Alcohol Exposure

      Feature Of The Week 02/22/15:  Case Western Reserve University Demostrates Using OCT to Rapidly Phenotype and Quantify Congenital Heart Defects Associated with Prenatal Alcohol Exposure

      The most commonly used method to analyze congenital heart defects involves serial sectioning and histology. However, this is often a time-consuming process where the quantification of cardiac defects can be difficult due to problems with accurate section registration. Here we demonstrate the advantages of using optical coherence tomography, a comparatively new and rising technology, to phenotype avian embryo hearts in a model of Fetal Alcohol Syndrome where a binge-like quantity of alcohol/ethanol was introduced at gastrulation. The rapid, consistent imaging protocols allowed for the immediate identification of cardiac anomalies, including ventricular septal defects and misaligned/missing vessels. Interventricular septum ...

      Read Full Article
    7. Using optical coherence tomography to rapidly phenotype and quantify congenital heart defects associated with prenatal alcohol exposure

      Using optical coherence tomography to rapidly phenotype and quantify congenital heart defects associated with prenatal alcohol exposure

      Background : The most commonly used method to analyze congenital heart defects involves serial sectioning and histology. However, this is often a time-consuming process where the quantification of cardiac defects can be difficult due to problems with accurate section registration. Here we demonstrate the advantages of using optical coherence tomography, a comparatively new and rising technology, to phenotype avian embryo hearts in a model of Fetal Alcohol Syndrome where a binge-like quantity of alcohol/ethanol was introduced at gastrulation. Results : The rapid, consistent imaging protocols allowed for the immediate identification of cardiac anomalies, including ventricular septal defects and misaligned/missing vessels ...

      Read Full Article
    8. Capturing structure and function in an embryonic heart with biophotonic tools

      Capturing structure and function in an embryonic heart with biophotonic tools

      Disturbed cardiac function at an early stage of development has been shown to correlate with cellular/molecular, structural as well as functional cardiac anomalies at later stages culminating in the congenital heart defects (CHDs) that present at birth. While our knowledge of cellular and molecular steps in cardiac development is growing rapidly, our understanding of the role of cardiovascular function in the embryo is still in an early phase. One reason for the scanty information in this area is that the tools to study early cardiac function are limited. Recently developed and adapted biophotonic tools may overcome some of the ...

      Read Full Article
    9. Three-dimensional correction of conduction velocity in the embryonic heart using integrated optical mapping and optical coherence tomography

      Three-dimensional correction of conduction velocity in the embryonic heart using integrated optical mapping and optical coherence tomography

      Optical mapping (OM) of cardiac electrical activity conventionally collects information from a three-dimensional (3-D) surface as a two-dimensional (2-D) projection map. When applied to measurements of the embryonic heart, this method ignores the substantial and complex curvature of the heart surface, resulting in significant errors when calculating conduction velocity, an important electrophysiological parameter. Optical coherence tomography (OCT) is capable of imaging the 3-D structure of the embryonic heart and accurately characterizing the surface topology. We demonstrate an integrated OCT/OM imaging system capable of simultaneous conduction mapping and 3-D structural imaging. From these multimodal data, we obtained 3-D activation maps ...

      Read Full Article
    10. Ethanol exposure alters early cardiac function in the looping heart: a mechanism for congenital heart defects?

      Ethanol exposure alters early cardiac function in the looping heart: a mechanism for congenital heart defects?

      Alcohol-induced congenital heart defects (CHDs) are frequently among the most life-threatening and require surgical correction in newborns. The etiology of these defects, collectively known as Fetal Alcohol Syndrome (FAS), has been the focus of much study, particularly involving cellular and molecular mechanisms. Few studies have addressed the influential role of altered cardiac function in early embryogenesis, due to a lack of tools with the capability to assay tiny beating hearts. To overcome this gap in our understanding, we used optical coherence tomography (OCT), a non-destructive imaging modality capable of micrometer-scale resolution imaging, to rapidly and accurately map cardiovascular structure and ...

      Read Full Article
    11. OCT News 2013 Student Paper Awarded to Pei Ma from Case Western Reserve University

      OCT News 2013 Student Paper Awarded to Pei Ma from Case Western Reserve University

      Pei Ma from Case Western Reserve University was a winner of the 2013 OCT News Student Paper Award for her submission “Developing Technologies for Electrophysiology Imaging in Embryonic Hearts.” Below is a summary of her work: Abstract: Congenital heart defects (CHDs) are one of the most common and devastating birth defects. Abnormal electrical activity at early stage of heart development can lead to severe CHDs. However, most developmental cardiology studies have not addressed the influential role of electrical activity in CHD etiology due to difficulties in early stages such as the embryonic hearts being too fragile for electrode recording, signal ...

      Read Full Article
    12. 4D shear stress maps of the developing heart using Doppler optical coherence tomography

      4D shear stress maps of the developing heart using Doppler optical coherence tomography

      Accurate imaging and measurement of hemodynamic forces is vital for investigating how physical forces acting on the embryonic heart are transduced and influence developmental pathways. Of particular importance is blood flow-induced shear stress, which influences gene expression by endothelial cells and potentially leads to congenital heart defects through abnormal heart looping, septation, and valvulogenesis. However no imaging tool has been available to measure shear stress on the endocardium volumetrically and dynamically. Using 4D structural and Doppler OCT imaging, we are able to accurately measure the blood flow in the heart tube in vivo and to map endocardial shear stress throughout ...

      Read Full Article
    13. Optical coherence tomography captures rapid hemodynamic responses to acute hypoxia of the embryonic cardiovascular system of Early Embryos

      Optical coherence tomography captures rapid hemodynamic responses to acute hypoxia of the embryonic cardiovascular system of Early Embryos

      Background.The trajectory to heart defects may start in tubular and looping heart stages when detailed analysis of form and function is difficult by currently available methods. We used a novel method, Doppler optical coherence tomography (OCT), to follow changes in cardiovascular function in quail embryos during acute hypoxic stress. Chronic fetal hypoxia is a known risk factor for congenital heart diseases (CHDs). Decreased fetal heart rates during maternal obstructive sleep apnea suggest that studying fetal heart responses under acute hypoxia is warranted.Results.We captured responses to hypoxia at the critical looping heart stages. Doppler OCT revealed detailed vitelline ...

      Read Full Article
    14. Optical Coherence Tomography Imaging of Early Quail Embryos

      Optical Coherence Tomography Imaging of Early Quail Embryos
      Congenital heart defects (CHDs) affect thousands of newborns each year in the United States. Recent research using animal model systems indicates that the abnormal function of the early tubular heart precedes structural defects such as septal defects. Optical coherence tomography (OCT) is an imaging modality that can provide high spatial and temporal resolution to study both the structure and the function of the tubular heart. With technical advances in OCT imaging speed, especially with frequency domain OCT and image-based retrospective gating, it is now possible to image a beating avian embryonic heart in three dimensions under physiological conditions and follow ...
      Read Full Article
    15. High-Speed Optical Coherence Tomography Imaging of the Beating Avian Embryonic Heart

      High-Speed Optical Coherence Tomography Imaging of the Beating Avian Embryonic Heart
      Congenital heart defects (CHDs) affect thousands of newborns each year in the United States. Recent research using animal model systems indicates that the abnormal function of the early tubular heart precedes structural defects such as septal defects. Optical coherence tomography (OCT) is an imaging modality that can provide high spatial and temporal resolution to study both the structure and the function of the tubular heart. With technical advances in OCT imaging speed, especially with frequency domain OCT and image-based retrospective gating, it is now possible to image a beating avian embryonic heart in three dimensions under physiological conditions and follow ...
      Read Full Article
    16. Measuring hemodynamics in the developing heart tube with four-dimensional gated Doppler optical coherence tomography

      Measuring hemodynamics in the developing heart tube with four-dimensional gated Doppler optical coherence tomography

      Hemodynamics is thought to play a major role in heart development, yet tools to quantitatively assess hemodynamics in the embryo are sorely lacking. The especially challenging analysis of hemodynamics in the early embryo requires new technology. Small changes in blood flow could indicate when anomalies are initiated even before structural changes can be detected. Furthermore, small changes in the early embryo that affect blood flow could lead to profound abnormalities at later stages. We present a demonstration of 4-D Doppler optical coherence tomography (OCT) imaging of structure and flow, and present several new hemodynamic measurements on embryonic avian hearts at ...

      Read Full Article
    1-16 of 16
  1. Categories

    1. Applications:

      Art, Cardiology, Dentistry, Dermatology, Developmental Biology, Gastroenterology, Gynecology, Microscopy, NDE/NDT, Neurology, Oncology, Ophthalmology, Other Non-Medical, Otolaryngology, Pulmonology, Urology
    2. Business News:

      Acquisition, Clinical Trials, Funding, Other Business News, Partnership, Patents
    3. Technology:

      Broadband Sources, Probes, Tunable Sources
    4. Miscellaneous:

      Jobs & Studentships, Student Theses, Textbooks
  2. Topics in the News

    1. (16 articles) Case Western Reserve University
    2. (1 articles) American Heart Association
    3. (1 articles) Brigham and Women’s Hospital
    4. (1 articles) University of Bologna
    5. (1 articles) University of Cambridge
    6. (1 articles) FDA
    7. (1 articles) Notal Vision
    8. (1 articles) Topcon Medical Systems
    9. (1 articles) Tomey Corporation
  3. Popular Articles

  4. Picture Gallery

    Measuring hemodynamics in the developing heart tube with four-dimensional gated Doppler optical coherence tomography High-Speed Optical Coherence Tomography Imaging of the Beating Avian Embryonic Heart Optical Coherence Tomography Imaging of Early Quail Embryos Optical coherence tomography captures rapid hemodynamic responses to acute hypoxia of the embryonic cardiovascular system of Early Embryos 4D shear stress maps of the developing heart using Doppler optical coherence tomography OCT News 2013 Student Paper Awarded to Pei Ma from Case Western Reserve University Ethanol exposure alters early cardiac function in the looping heart: a mechanism for congenital heart defects? Capturing structure and function in an embryonic heart with biophotonic tools Using optical coherence tomography to rapidly phenotype and quantify congenital heart defects associated with prenatal alcohol exposure Feature Of The Week 02/22/15:  Case Western Reserve University Demostrates Using OCT to Rapidly Phenotype and Quantify Congenital Heart Defects Associated with Prenatal Alcohol Exposure Comparison of Anterior Segment Measurements with a New Multifunctional Unit and Five Other Devices Efficacy of Notal Vision Home OCT demonstrated by a series of scientific and clinical work