Category: Doppler

1. OCT Companies in the News

   (3 articles) Carl Zeiss Meditec

   (2 articles) Physical Sciences Incorporated

   (2 articles) Superlum

   (2 articles) Thorlabs

   (1 articles) NKT Photonics

   (1 articles) Canon Medical Systems

   (1 articles) LuMend, Inc.

   (1 articles) Basler

   (1 articles) Cambridge Technology

   (1 articles) Volcano

2. OCT Products in the News

   (1 articles) Zeiss Stratus OCT

3. Organizations in the News

   (9 articles) University of Oulu

   (9 articles) Medical University of Vienna

   (8 articles) UC Irvine

   (8 articles) Keck School of Medicine

   (8 articles) Oregon Health & Science University

   (8 articles) Duke University

   (7 articles) Dresden University of Technology

   (7 articles) University of Tsukuba

   (7 articles) Nicolaus Copernicus University

   (6 articles) Moscow State University

4. People in the News

   (13 articles) Joseph A. Izatt

   (10 articles) Zhongping Chen

   (8 articles) Ruikang K. Wang

   (7 articles) Alexander V. Bykov

   (7 articles) Edmund Koch

   (7 articles) Julia Walther

   (7 articles) Maciej Szkulmowski

   (7 articles) Andrzej A. Kowalczyk

   (7 articles) Yoshiaki Yasuno

   (7 articles) Shuichi Makita

1. Imaging of subcutaneous blood vessels and flow velocity profiles by optical coherence tomography

   Explore Article SpringerLink Home (Mar 11 2010) Dermatology , Doppler

   We have applied a compact low power rapid scanning Doppler Optical Coherence Tomography system to monitor multi-dimensional velocity profiles within the complex vessels and simultaneous real-time non-invasive imaging of skin tissues morphology in vivo, in the wavelength range of 1.3–1.5 nm. Optical clearing of skin tissues has been utilized to achieve depth of OCT images up to 1.7 mm. Current approach enables applying low-power (0.4–0.5 mW) and low-noise broadband near-infrared light sources and obtaining OCT images with down to 12 μm spatial resolution. Two-dimensional time-domain OCT images of complex flow velocity profiles in blood vessel phantom and in vivo subcutaneous ...
   

   Comment on Article Mentions:   Medical University of Vienna   University of Otago   Igor V. Meglinski

2. High-sensitive blood flow imaging of the retina and choroid by using double-beam optical coherence angiography

   Explore Article SPIE Digital Library (Mar 5 2010) Ophthalmology , Doppler

   Wide-field and high-sensitive Doppler optical coherence angiography of the posterior human eye has been demonstrated. High-sensitive phase-resolved spectral-domain optical coherence tomography using the superluminescent diode with the central wavelength of 840 nm and bandwidth of 50 nm (FWHM) is developed. Two OCT signals with a time separation are acquired simultaneously with double sampling beams divided by using a Wollaston prism and a polarization-sensitive spectrometer consisting of two line scan cameras. The total power of two beams on the cornea is 700 µW. The line scan rate of cameras is 27 kHz and each OCT channel has the sensitivity of 93 ...
   

   Comment on Article Mentions:   Shuichi Makita   Yoshiaki Yasuno   Masahiro Miura

3. True velocity mapping using joint spectral and time domain optical coherence tomography

   Explore Article SPIE Digital Library (Mar 2 2010) Ophthalmology , Doppler

   We present both axial and transverse components estimation using joint Spectral and Time domain Optical Coherence Tomography (STdOCT) method. Whereas axial component of velocity vector can be determined from the time-dependent Doppler beating frequency, the transverse component can be assessed by the analysis of the broadening of flow velocity profiles (Doppler bandwidth). This enables us to quantitatively determine the absolute value of the velocity vector. The accurate analyses are performed using well-defined flow of Intralipid solution in the glass capillary. This enables performing in vivo imaging and allows to calculate velocity maps of the retinal vasculature
   

   Comment on Article Mentions:   Maciej Wojtkowski   Nicolaus Copernicus University   Andrzej A. Kowalczyk

4. Functional Doppler optical coherence tomography for cortical blood flow imaging

   Explore Article SPIE Digital Library (Mar 2 2010) Doppler

   Optical methods have been widely used in basic neuroscience research to study the cerebral blood flow dynamics in order to overcome the low spatial resolution associated with magnetic resonance imaging and positron emission tomography. Although laser Doppler imaging and laser speckle imaging can map out en face cortical hemodynamics and columns, depth resolution is not available. Two-photon microscopy has been used for mapping cortical activity. However, flow measurement requires fluorescent dye injection, which can be problematic. The noninvasive and high resolution tomographic capabilities of optical coherence tomography make it a promising technique for mapping depth resolved cortical blood flow. Here, ...
   

   Comment on Article Mentions:   Zhongping Chen   UC Irvine

5. The study of effects of pore architecture in chitosan scaffolds on the fluid flow pattern by Doppler OCT

   Explore Article SPIE Digital Library (Feb 24 2010) Doppler

   Optimizing and fully understanding the dynamic culture conditions in tissue engineering could accelerate exploration of this new technique into a promising therapy in the medical field. Scaffolds used in tissue engineering usually are highly porous with various pore architecture depending on techniques that manufacture them. Perfusing culture fluid through a scaffold in a bioreactor has proven efficient in enhancing the exchange of nutrients and gas within cell-scaffold constructs. Upon perfusion, flowing fluid in pores inevitably produces shear stress on the wall of the pores, which will in turn induce cellular response for the cells possessing mechanotransducers. Thus, establishing a relationship ...
   

   Comment on Article Mentions:   Ruikang K. Wang   Ying Yang   Oregon Health & Science University

6. Full-range spectral domain Doppler optical coherence tomography

   Explore Article SPIE Digital Library (Feb 23 2010) Doppler

   Spectral domain optical coherence tomography (SD-OCT) systems achieve higher sensitivities compared to time domain OCT systems. However, one of the main challenges in SD-OCT is the obscuring object structure called "ghost image" or "mirror image" that arises from the Fourier transform of a real function. We have designed and developed a phaseshifting- based full-range SD-OCT system that we refer to as the dual detection full range SD-OCT. The proposed technique simultaneously obtains the quadrature components of a complex spectral interference. Therefore, the technique enables full range imaging without any loss of speed and is intrinsically less sensitive to movements of ...
   

   Comment on Article Mentions:   University of Central Florida   Kye-Sun Lee   University of Rochester

7. A gel-based skin and blood flow model for a Doppler optical coherence tomography (DOCT) imaging system

   Explore Article SPIE Digital Library (Feb 23 2010) Dermatology , Doppler

   Since its discovery in 1842 by Christian Johann Doppler, the Doppler Effect has had many applications in the scientific world. In recent years, the phenomenon has been integrated with Optical Coherence Tomography (OCT) yielding Doppler Optical Coherence Tomography (DOCT), a technique that is useful for high-resolution imaging of the skin microcirculation. However, interpretation of DOCT images is rather challenging. Thus, our study aims to aid understanding of DOCT images with respect to parameters of microcirculation components such as blood vessel size, depth and angular position. To this end, we have constructed a gel-based tissue and blood-flow model for performing DOCT ...
   

   Comment on Article Mentions:   University of Limerick

8. Real-time bulk motion insensitive flow segmentation algorithm for doppler spectral optical coherence tomography

   Explore Article SPIE Digital Library (Feb 22 2010) Doppler

   We present a simple and efficient numerical technique for segmentation retinal and choroidal blood vasculature with bulk motion correction in functional Doppler Spectral Optical Coherence Tomography (Doppler SOCT). The technique uses local variance of velocity tomogram which is higher in the areas of the tomogram with internal flow. The resulting variance map reveals the position of vessels. This can be used either for vessel segmentation purposes or for masking the vessels on velocity tomograms. The remaining velocity information is connected only with static structure velocity offset. As only Fourier transformations are used in calculations the algorithm removes the bulk motion ...
   

   Comment on Article Mentions:   Maciej Wojtkowski   Nicolaus Copernicus University   Andrzej A. Kowalczyk

9. Multi-beam resolution video-rate swept-source optical coherence tomography (OCT) provides endogenous contrast for in vivo blood flow independent of flow direction

   Explore Article SPIE Digital Library (Feb 19 2010) Doppler

   Optical coherence tomography (OCT) allows non-invasive imaging of sub-surface structures in vivo, ideally without a need for target preparation. In conventional OCT, the contrast for blood vessels depends on a variety of factors and can be challenging. Speckle variance has been recognized as a method to enhance contrast for blood flow without the application of contrast agents in OCT images. Here, we demonstrate the possibility of extracting blood flow information from a volumetric OCT datasets that was obtained routinely from a human participant. We used a commercially available OCT system with a clinical CE-mark. The light source has a central ...
   

   Comment on Article Mentions:   Michelson Diagnostics   Florian Bazant-Hegemark   Jon Holmes

10. Investigations of the intravascular backscattering distribution of light in optical coherence tomography

    Explore Article SPIE Digital Library (Feb 12 2010) Cardiology , Doppler

    The inhomogeneous backscattering distribution of low-coherent light in blood vessels, which appears as waisted double fan-shaped intensity pattern, is investigated in an in vivo mouse model and flow phantom measurements using high resolution spectral domain optical coherence tomography in the 1.3 µm wavelength region. Based on a predicted orientation of the red blood cells towards laminar flow, an angular modulation of the corresponding backscattering crosssection inside the vessels is assumed. In combination with the signal attenuation in depth by absorption and scattering, a simple model of the intravascular intensity modulation is derived. The suitability of the model is demonstrated exemplarily ...
    

    Comment on Article Mentions:   Edmund Koch   Julia Walther   NKT Photonics

11. Multiple and dependent scattering effects in Doppler optical coherence tomography

    Explore Article opticsinfobase.org (Feb 11 2010) Doppler

    Doppler optical coherence tomography (OCT) is a technique to image tissue morphology and to measure flow in turbid media. In its most basic form, it is based on single (Mie) scattering. However, for highly scattering and dense media multiple and concentration dependent scattering can occur. For Intralipid solutions with varying scattering strength, the effect of multiple and dependent scattering on the OCT signal attenuation and Doppler flow is investigated. We observe a non-linear increase in the OCT signal attenuation rate and an increasingly more distorted Doppler OCT flow profile with increasing Intralipid concentration. The Doppler OCT attenuation and flow measurements ...
    

    Comment on Article Mentions:   Academic Medical Center at the University of Amsterdam   Dirk J. Faber   University of Oulu

12. Quantitative cerebral blood flow with Optical Coherence Tomography

    Explore Article opticsinfobase.org (Jan 22 2010) Doppler

    Vivek J. Srinivasan, Sava Sakadžić, Iwona Gorczynska, Svetlana Ruvinskaya, Weicheng Wu, James G. Fujimoto, David A. BoasAbsolute measurements of cerebral blood flow (CBF) are an important endpoint in studies of cerebral pathophysiology. Currently no accepted method exists for in vivo longitudinal monitoring of CBF with high resolution in rats and mice. Using three-dimensional Doppler Optical Coherence Tomography and ... [Opt. Express 18, 2477-2494 (2010)]
    

    Comment on Article Mentions:   James G. Fujimoto   Vivek J. Srinivasan   Iwona Gorczyńska

13. Doppler optical coherence tomography for interventional cardiovascular guidance: in vivo feasibility and forward-viewing probe flow phantom demonstration

    Explore Article SPIE Digital Library (Jan 19 2010) Cardiology , Doppler , Probes

    We demonstrate the potential of a forward-looking Doppler optical coherence tomography (OCT) probe for color flow imaging in several commonly seen narrowed artery morphologies. As a proof of concept, we present imaging results of a surgically exposed thrombotic occlusion model that was imaged superficially to demonstrate that Doppler OCT can identify flow within the recanalization channels of a blocked artery. We present Doppler OCT images in which the flow is nearly antiparallel to the imaging direction. These images are acquired using a flexible 2.2-mm-diam catheter that used electrostatic actuation to scan up to 30 deg ahead of the distal end. ...
    

    Comment on Article Mentions:   Sunnybrook Health Sciences Centre   Graham A. Wright   Ontario Cancer Institute

14. Parabolic BM-scan technique for full range Doppler spectral domain optical coherence tomography

    Explore Article opticsinfobase.org (Jan 12 2010) Doppler

    A full range spectral domain optical coherence tomography (SD-OCT) technique that relies on the linear phase modulation of one of the interferometer arms has been widely utilized. Although this method is useful, the mirror image elimination is not perfect for samples in which regions with high axial motion exist. In this paper, we introduce a new modulation pattern to overcome this mirror image elimination failure. This new modulation is a parabolic phase modulation in the transverse scanning direction, and is applied to the SD-OCT reference beam by an electro-optic modulator. Flow phantom and in vivo experiments demonstrate that for moving ...
    

    Comment on Article Mentions:   Shuichi Makita   Yoshiaki Yasuno   University of Tsukuba

15. Transit-time analysis based on delay-encoded beam shape for velocity vector quantification by spectral-domain Doppler optical coherence tomography

    Explore Article opticsinfobase.org (Jan 11 2010) Doppler

    We propose a transit-time based method to ascertain the azimuth angle of a velocity vector by spectral-domain Doppler optical coherence tomography (DOCT), so that three-dimensional (3-D) velocity vector can be quantified. A custom-designed slit plate with predetermined slit orientation is placed into the sample beam to create three delay-encoded sub-beams of different beam shape for sample probing. Based on the transit-time analysis for Doppler bandwidth, the azimuth angle within 90° range is evaluated by exploitation of the complex signals corresponding to three path length delays. 3-D velocity vector is quantified through further estimating of Doppler angle and flow velocity by ...
    

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