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(10 articles) University of Oulu
(10 articles) Medical University of Vienna
(8 articles) Dresden University of Technology
(8 articles) University of Southern California
(8 articles) Oregon Health & Science University
(8 articles) Case Western Reserve University
(7 articles) Moscow State University
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Doppler imaging with dual-detection full-range frequency domain optical coherence tomography
Explore Article opticsinfobase.org (Aug 10 2010)
Most of full-range techniques for Frequency Domain Optical Coherence Tomography (FD-OCT) reported to date utilize the phase relation between consecutive axial lines to reconstruct a complex interference signal and hence may exhibit degradation in either mirror image suppression performance or detectable velocity dynamic range or both when monitoring a moving sample such as flow activity. We have previously reported a technique of mirror image removal by simultaneous detection of the quadrature components of a complex spectral interference called a Dual-Detection Frequency Domain OCT (DD-FD-OCT) [Opt. Lett. 35, 1058-1060 (2010)]. The technique enables full range imaging without any loss of acquisition ...
Comment on Article Mentions: Jannick P. Rolland Panomsak Meemon Kye-Sung Lee
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Signal power decrease due to fringe washout as an extension of the limited Doppler flow measurement range in spectral domain optical coherence tomography
Explore Article SPIE Digital Library (Jul 23 2010)
The recently introduced new phase-dependent Doppler model for spectral domain optical coherence tomography (SD OCT) has shown that the simple linear relation between the Doppler phase shift and the axial velocity component of an obliquely moving sample is not valid. Additionally, for nearly transverse sample motion with high velocities the phase shift will approach a constant value. Consequently, for small Doppler angles the velocity measurement range of the phase-resolved Doppler analysis is limited in SD OCT. Since these undesirable small Doppler angles can not be prevented, for example, in the in vivo 3-D measurement, we introduce a novel method extending ...
Comment on Article Mentions: Julia Walther Dresden University of Technology Henning Morawietz
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Doppler optical coherence tomography for imaging of brain hemodynamics
Explore Article Home: SPIE.org (Jul 6 2010)
Advanced microscopic techniques enable depth-resolved imaging of changes in blood flow during brain activation. ptical imaging has become an important tool in neuroscience research.1 Using methods such as optical intrinsic signal imaging (OISI), laser-Doppler imaging, and laser-speckle imaging, investigators can record changes in blood flow and blood volume in the brain, as well as alterations in blood oxygen concentration, in response to different types of stimulation. By measuring these changes, they can gain deeper insight into the functioning of the brain, which in turn can contribute to better understanding of a range of behaviors and conditions. However, these techniques typically ...
Comment on Article Mentions: James G. Fujimoto Alex E. Cable Vivek J. Srinivasan
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High-velocity-flow imaging with real-time Doppler optical coherence tomography
Explore Article opticsinfobase.org (May 27 2010)
We present a real-time time-domain Doppler optical coherence tomography (OCT) system based on the zero-crossing method for velocity measurements of fluid flows with attainable velocities up to 10 m/s. In the current implementation, one-dimensional and two-dimensional velocity profiles of fluid flows ranging from 1 cm/s to more than 3 m/s were obtained for both laminar and turbulent flows. The line rate was approximately 500 Hz, and the images were treated in real time. This approach has the advantage of providing reliable velocity maps free from phase aliasing or other artifacts common to several OCT systems. The system is particularly well ...
Comment on Article Mentions: Ecole Polytechnique de Montréal Romain Maciejko
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Effect of light scattering superficial layer on the accuracy of flow velocity profiles measurements by Doppler optical coherence tomography
Explore Article SPIE Digital Library (May 18 2010)
Doppler Optical Coherence Tomography (DOCT) is a modern technique used for accurate measurements of blood flow in the superficial layers of human skin, retina or other tissues and their phantoms. In this work, we considered the effect of both static and dynamic superficial layer of the scattering medium on the measured velocity of a flow located beneath this layer. In the case of static layer a tissue phantom consisting of a plain glass capillary (inner size 0.3 × 3 mm) embedded into a slab of Intralipid solution mimicking human skin was designed. Flow velocity profiles were measured at different embedding ...
Comment on Article Mentions: Risto A. Myllylä Alexander V. Bykov Alexander V. Priezzhev
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Velocity Variation Assessment of Red Blood Cell Aggregation with Spectral Domain Doppler Optical Coherence Tomography
Explore Article SpringerLink Home (May 15 2010)
We propose spectral domain Doppler optical coherence tomography (SD-D-OCT) to qualitatively measure red blood cell aggregation. Variance/standard deviation (SD) of the Doppler frequency spectrum in Doppler variance imaging of flowing blood under shearing conditions was developed as a new aggregation index. In in vitro microchannel-flow experiments, porcine blood at various hematocrits with aggregation characteristics induced by dextran 500 or at the presence of plasma fibrinogen was measured by a SD-D-OCT system with a spectrum centered at 1310 nm. The effects of shear rate, hematocrit, aggregation level on the SD values were investigated. The results demonstrate that Doppler variance imaging using ...
Comment on Article Mentions: Zhongping Chen UC Irvine Lingfeng Yu
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Doppler optical coherence tomography in cardiovascular applications
Explore Article SpringerLink Home (Apr 28 2010)
Abstract The study of flow dynamics in complex geometry vessels is highly important in various biomedical applications where the knowledge of the mechanic interactions between the moving fluid and the housing media plays a key role for the determination of the parameters of interest, including the effect of blood flow on the possible rupture of atherosclerotic plaques. Doppler Optical Coherence Tomography (DOCT), as a functional extension of Optical Coherence Tomography (OCT), is an optic, non-contact, noninvasive technique able to achieve detailed analysis of the flow/vessel interactions. It allows simultaneous high resolution imaging (∼10 µm typical) of the morphology and composition ...
Comment on Article Mentions: Medical University of Vienna University of Otago University of Sheffield
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Optimized speckle variance OCT imaging of microvasculature
Explore Article opticsinfobase.org (Apr 14 2010)
We optimize speckle variance optical coherence tomography (svOCT) imaging of microvasculature in high and low bulk tissue motion scenarios. To achieve a significant level of image contrast, frame rates must be optimized such that tissue displacement between frames is less than the beam radius. We demonstrate that higher accuracy estimates of speckle variance can enhance the detection of capillaries. These findings are illustrated in vivo by imaging the dorsal window chamber model (low bulk motion). We also show svOCT imaging of the nonstabilized finger (high bulk motion), using optimized imaging parameters, demonstrating better vessel detection than Doppler OCT.
Comment on Article Mentions: Victor X. D. Yang Beau A. Standish Michael K. K. Leung
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Imaging of subcutaneous blood vessels and flow velocity profiles by optical coherence tomography
Explore Article SpringerLink Home (Mar 11 2010)
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
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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)
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
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True velocity mapping using joint spectral and time domain optical coherence tomography
Explore Article SPIE Digital Library (Mar 2 2010)
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
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Functional Doppler optical coherence tomography for cortical blood flow imaging
Explore Article SPIE Digital Library (Mar 2 2010)
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 Lingfeng Yu
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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)
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
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Full-range spectral domain Doppler optical coherence tomography
Explore Article SPIE Digital Library (Feb 23 2010)
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-Sung Lee University of Rochester
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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)
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
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Great video Jim!
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Dear Prof. Dr. Gary S. Mintz, You are an extraordinary expert in imaging, an intelligence ...
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