1. Vivek J. Srinivasan

    0 Comments Leave a Comment

    1-15 of 80 1 2 3 4 5 6 »
    1. Mentioned In 80 Articles

    2. Incoherent excess noise spectrally encodes broadband light sources

      Incoherent excess noise spectrally encodes broadband light sources
      Across optics and photonics, excess intensity noise is often considered a liability. Here, we show that excess noise in broadband supercontinuum and superluminescent diode light sources encodes each spectral channel with unique intensity fluctuations, which actually serve a useful purpose. Specifically, we report that excess noise correlations can both characterize the spectral resolution of spectrometers and enable cross-calibration of their wavelengths across a broad bandwidth. Relative to previous methods that ...
      Read Full Article
    3. Water wavenumber calibration for visible light optical coherence tomography

      Water wavenumber calibration for visible light optical coherence tomography
      Significance : Visible light optical coherence tomography (OCT) is emerging for spectroscopic and ultrahigh resolution imaging, but challenges remain. Depth-dependent dispersion limits retinal image quality and current correction approaches are cumbersome. Inconsistent group refractive indices during image reconstruction also limit reproducibility. Aim: To introduce and evaluate water wavenumber calibration (WWC), which corrects depth-dependent dispersion and provides an accurate depth axis in water. Approach: Enabled by a visible light OCT spectrometer configuration ...
      Read Full Article
    4. Visibility of microvessels in Optical Coherence Tomography Angiography depends on angular orientation

      Visibility of microvessels in Optical Coherence Tomography Angiography depends on angular orientation
      OCT Angiography (OCTA) is a widespread tool for depth‐resolved imaging of chorioretinal vasculature with single microvessel resolution. To improve the clinical interpretation of OCTA, the conditions affecting visualization of microvessels must be defined. Here we inject a scattering plasma tracer (Intralipid) during OCTA imaging of the anesthetized rat eye. In the retina, we find that interlaminar (vertical) vessels that connect laminae have one‐fourth to one‐third the OCTA ...
      Read Full Article
    5. Noninvasive, in vivo rodent brain optical coherence tomography at 2.1  microns

      Noninvasive, in vivo rodent brain optical coherence tomography at 2.1  microns
      n biological tissue, longer near-infrared wavelengths generally experience less scattering and more water absorption. Here we demonstrate an optical coherence tomography (OCT) system centered at 2.1 microns, whose bandwidth falls in the 2.2 micron water absorption optical window, for in vivo imaging of the rodent brain. We show in vivo that at 2.1 microns, the OCT signal is actually attenuated less in cranial bone than at 1 ...
      Read Full Article
    6. Dynamic Contrast Optical Coherence Tomography reveals laminar microvascular hemodynamics in the mouse neocortex in vivo

      Dynamic Contrast Optical Coherence Tomography reveals laminar microvascular hemodynamics in the mouse neocortex in vivo
      Studies of flow-metabolism coupling often presume that microvessel architecture is a surrogate for blood flow. To test this assumption, we introduce an in vivo Dynamic Contrast Optical Coherence Tomography (DyC-OCT) method to quantify layer-resolved microvascular blood flow and volume across the full depth of the mouse neocortex, where the angioarchitecture has been previously described . First, we cross-validate average DyC-OCT cortical flow against conventional Doppler OCT flow. Next, with laminar DyC-OCT ...
      Read Full Article
    7. Compensating spatially dependent dispersion in visible light OCT

      Compensating spatially dependent dispersion in visible light OCT
      Visible light optical coherence tomography (OCT) has recently emerged in retinal imaging, with claims of micrometer-scale axial resolution and multi-color (sub-band) imaging. Here, we show that the large dispersion of optical glass and aqueous media, together with broad optical bandwidths often used in visible light OCT, compromises both of these claims. To rectify this, we introduce the notion of spatially dependent (i.e., depth and transverse position-dependent) dispersion. We use ...
      Read Full Article
    8. Quantitative Optical Coherence Tomography Methods for Functional Microvascular Imaging (Thesis)

      Quantitative Optical Coherence Tomography Methods for Functional Microvascular Imaging (Thesis)
      In recent years, the importance of blood flow distribution has been highlighted in a wide range of diseases that involve the cerebral microvasculature. Specifically, microvascular heterogeneity, related to the non-uniform distribution of blood flow through the microvasculature, is an important parameter that is critical to the efficacy of oxygen extraction. As increased heterogeneity may lead to oxygen insufficiency, even with blood flow above ischemic levels, heterogeneity may be an important ...
      Read Full Article
    9. Visible light optical coherence microscopy imaging of the mouse cortex with femtoliter volume resolution

      Visible light optical coherence microscopy imaging of the mouse cortex with femtoliter volume resolution
      Most flying-spot Optical Coherence Tomography (OCT) and Optical Coherence Microscopy (OCM) systems use a symmetric confocal geometry, where the detection path retraces the illumination path starting from and ending with the spatial mode of a single mode optical fiber. Here, we describe a visible light OCM instrument that breaks this symmetry to improve transverse resolution without sacrificing collection efficiency in scattering tissue. This was achieved by overfilling a 0.3 ...
      Read Full Article
    10. Visible Light Optical Coherence Microscopy of the Brain with Isotropic Femtoliter Resolution In Vivo

      Visible Light Optical Coherence Microscopy of the Brain with Isotropic Femtoliter Resolution In Vivo
      Most flying-spot Optical Coherence Tomography (OCT) and Optical Coherence Microscopy (OCM) systems use a symmetric confocal geometry, where the detection path retraces the illumination path starting from and ending with the spatial mode of a single mode optical fiber. Here, we describe a visible light OCM instrument that breaks this symmetry to improve transverse resolution without sacrificing collection efficiency. This was achieved by overfilling a water immersion objective on the ...
      Read Full Article
    11. Can OCT Angiography Be Made a Quantitative Blood Measurement Tool?

      Can OCT Angiography Be Made a Quantitative Blood Measurement Tool?
      Optical Coherence Tomography Angiography (OCTA) refers to a powerful class of OCT scanning protocols and algorithms that selectively enhance the imaging of blood vessel lumens, based mainly on the motion and scattering of red blood cells (RBCs). Though OCTA is widely used in clinical and basic science applications for visualization of perfused blood vessels, OCTA is still primarily a qualitative tool. However, more quantitative hemodynamic information would better delineate disease ...
      Read Full Article
    12. Structural and functional human retinal imaging with a fiber-based visible light OCT ophthalmoscope

      Structural and functional human retinal imaging with a fiber-based visible light OCT ophthalmoscope
      The design of a multi-functional fiber-based Optical Coherence Tomography (OCT) system for human retinal imaging with 2 micron axial resolution in tissue is described. A detailed noise characterization of two supercontinuum light sources with different pulse repetition rates is presented. The higher repetition rate and lower noise source is found to enable a sensitivity of 96 dB with 0.15 mW light power at the cornea and a 98 microsecond ...
      Read Full Article
    13. Dynamic contrast optical coherence tomography images transit time and quantifies microvascular plasma volume and flow in the retina and choriocapillaris

      Dynamic contrast optical coherence tomography images transit time and quantifies microvascular plasma volume and flow in the retina and choriocapillaris
      Despite the prevalence of optical imaging techniques to measure hemodynamics in large retinal vessels, quantitative measurements of retinal capillary and choroidal hemodynamics have traditionally been challenging. Here, a new imaging technique called dynamic contrast optical coherence tomography (DyC-OCT) is applied in the rat eye to study microvascular blood flow in individual retinal and choroidal layersin vivo. DyC-OCT is based on imaging the transit of an intravascular tracer dynamically as it ...
      Read Full Article
    14. Microstructural characterization of myocardial infarction with optical coherence tractography and two‐photon microscopy

      Microstructural characterization of myocardial infarction with optical coherence tractography and two‐photon microscopy
      Myocardial infarction leads to complex changes in the fiber architecture of the heart. Here, we present a novel optical approach to characterize these changes in intact hearts in three dimensions. Optical coherence tomography (OCT) was used to derive a depth‐resolved field of orientation on which tractography was performed. Tractography of healthy myocardium revealed a smooth linear transition in fiber inclination or helix angle from the epicardium to endocardium. Conversely ...
      Read Full Article
    15. Diagnostic performance of a novel 3D neuroretinal rim parameter for glaucoma using high-density volume scans

      Diagnostic performance of a novel 3D neuroretinal rim parameter for glaucoma using high-density volume scans
      Purpose To describe optical coherence tomography angiography (OCTA) findings in multifocal choroiditis (MFC) with active lesions and to characterize the concordance between the OCTA and other traditional imaging modalities. Design Reliability and validity analysis. Methods Patients with suspected choroidal neovascularization (CNV) or acute inflammatory lesions associated with MFC were assessed in this study. All participants underwent preliminary traditional multimodal imaging including color fundus photography, fundus autofluorescence, near-infrared reflectance imaging, spectral-domain ...
      Read Full Article
    16. Imaging and graphing of cortical vasculature using dynamically focused optical coherence microscopy angiography

      Imaging and graphing of cortical vasculature using dynamically focused optical coherence microscopy angiography
      Recently, optical coherence tomography (OCT) angiography has enabled label-free imaging of vasculature based on dynamic scattering in vessels. However, quantitative volumetric analysis of the vascular networks depicted in OCT angiography data has remained challenging. Multiple-scattering tails (artifacts specific to the imaging geometry) make automated assessment of vascular morphology problematic. We demonstrate that dynamically focused optical coherence microscopy (OCM) angiography with a high numerical aperture, chosen so the scattering length greatly ...
      Read Full Article
    17. 1-15 of 80 1 2 3 4 5 6 »
  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. About Vivek J. Srinivasan

    Vivek J. Srinivasan

    Vivek J. Srinivasan is Assistant Professor of Biomedical Engineering at the University of California Davis. Dr. Srinivasan received his B.S. and M.S. in Electrical Engineering from Stanford University, and my PhD in EECS (bioelectrical engineering area) at MIT. His lab recently moved to the UC Davis Biomedical Engineering Department from the Martinos Center for Biomedical Imaging in the Department of Radiology at MGH. The lab has developed a range of optical tools for diagnostics and basic science applications, focusing in particular on the quantitative study of organ physiology at the microscopic scale. Recent advances pioneered by the laboratory include all-optical methods of blood flow quantification, imaging of cytoarchitecture and myeloarchitecture with intrinsic contrast, and statistical methods and models of capillary speed quantification. They have applied these tools to study a wide range of questions, from the basis of neurovascular coupling to evolution of injury and recovery in ischemic stroke.

  3. Quotes

    1. There are some subjective and structural methods available now for detecting glaucoma and its progression.
      In Second Catalyst Research Team Sets Sights on Biomarker Discovery