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Dos Reis Gisele Fm GF 1Veterinary Medicine Department, Veterinary School, Garça, São Paulo, - - 2014
The qualitative and quantitative aspects of femoral artery blood flow waveform spectra were evaluated in 15 male and 15 female Persian and mixed breed domestic felines (Felis catus), which were healthy and not sedated, using duplex Doppler ultrasonography (DDU). Spectral Doppler demonstrated a biphasic characteristic in 16 (53.34%) of the ...
Vuong Barry - - 2014
We report a technique for blood flow detection using split spectrum Doppler optical coherence tomography (ssDOCT) that shows improved sensitivity over existing Doppler OCT methods. In ssDOCT, the Doppler signal is averaged over multiple sub-bands of the interferogram, increasing the SNR of the Doppler signal. We explore the parameterization of ...
Leitgeb Rainer A RA Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Waehringer Guertel 18-20, 1090 Vienna, - - 2014
Optical Coherence Tomography (OCT) has revolutionized ophthalmology. Since its introduction in the early 1990s it has continuously improved in terms of speed, resolution and sensitivity. The technique has also seen a variety of extensions aiming to assess functional aspects of the tissue in addition to morphology. One of these approaches ...
Vanderschueren Geraldine A K B GA Department of Neurology, Atrium Medical Centre, Heerlen, The - - 2014
Introduction Doppler sonography may detect increased intraneural blood flow of the median nerve in carpal tunnel syndrome (CTS). Objective Critically review the present literature about the diagnostic value of increased intraneural flow detected by sonography in CTS. Methods Systematic review of studies published between 1985 and 2013. Results The 7 ...
Talati Pratik P Neuroscience Program, Vanderbilt University, Nashville, TN, 37235; Department of Psychiatry, Vanderbilt University, Nashville, TN, - - 2014
The human hippocampal formation is characterized by anterior-posterior gradients of cell density, neurochemistry and hemodynamics. In addition, some functions are associated with specific subfields (subiculum, CA1-4, dentate gyrus) and regions (anterior and posterior). We performed contrast-enhanced, high-resolution T1-weighted 3T steady state (SS) imaging to investigate cerebral blood volume (CBV) gradients ...
Bohner Bíborka B Department of Physical Chemistry and Materials Science, University of Szeged, Szeged, H-6720, Hungary. - - 2014
We have analyzed the emerging precipitate pattern of calcium-oxalate in a flow system. The circular symmetry is broken because of the hydrodynamic instability at the tip of the underlying gravity current. The presence of a concentration gradient maintained by the flow leads to the enrichment of the thermodynamically unstable calcium ...
Hsiao Albert A Department of Radiology, Stanford University, Stanford, California, - - 2014
To determine whether it is feasible to use solely an accelerated 4D phase-contrast magnetic resonance imaging (4D-PC MRI) acquisition to quantify net and regurgitant flow volume through each of the cardiac valves. Accelerated, 4D-PC MRI examinations performed between March 2010 through June 2011 as part of routine MRI examinations for ...
Imamoglu E Y EY Zeynep Kamil Maternity and Children's Training and Research Hospital, Neonatal Intensive Care Unit Istanbul, Istanbul, - - 2014
Objective:The objective of this study is to investigate the effects of antenatal magnesium sulfate (MgSO4) on cerebral blood flow (CBF) velocities in preterm neonates.Study Design:In this prospective case-control study, we included 53 neonates born between 26 and 34 weeks of gestation. Twenty neonates were exposed to MgSO4 antenatally and 33 ...
Logallo Nicola N Department of Clinical Medicine, University of Bergen, Bergen, - - 2014
Ultrasound contrast agents (UCA) salvage a considerable number of transcranial Doppler (TCD) exams which would have failed because of poor bone window. UCA bolus injection causes an undesirable increase in measured blood flow velocity (BFV). The effect of UCA continuous infusion on measured BFV has not been investigated, and some ...
Xu Tiantian T Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, - - 2014
In previous studies, we proposed blood measurement using speckle size estimation, which estimates the lateral component of blood flow within a single image frame based on the observation that the speckle pattern corresponding to blood reflectors (typically red blood cells) stretches (i.e., is "smeared") if blood flow is in the ...
Peterson Lindsy M LM Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106 - - 2014
Doppler OCT (DOCT) can provide blood flow velocity information which is valuable for investigation of microvascular structure and function. However, DOCT is only sensitive to motion parallel with the imaging beam, so that knowledge of flow direction is needed for absolute velocity determination. Here, absolute volumetric flow is calculated by ...
Binder Ronald K RK St. Paul's Hospital, University of British Columbia, Vancouver, - - 2014
Background: Transcatheter aortic valve replacement (TAVR) is less invasive than surgical aortic valve replacement and may be preferred for patients, who refuse blood transfusions. Objectives: Our study sought to define transfusion rates in TAVR, identify predictors and develop recommendations for patients, who refuse transfusions. Methods: A large cohort of consecutive ...
Vachutka Jaromir - - 2014
The objective of this study is to investigate the effect of multiple dead elements in an ultrasound probe on the accuracy of Doppler ultrasound measurements. For this work, we used a specially designed ultrasound imaging system, the Ultrasonix Sonix RP, that provides the user with the ability to disable selected ...
Wang Bo B UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America; Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America; Department of Biostatistics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of - - 2014
To investigate gold nanorods (GNRs) as a contrast agent to enhance Doppler optical coherence tomography (OCT) imaging of the intrascleral aqueous humor outflow. A serial dilution of GNRs was scanned with a spectral-domain OCT device (Bioptigen, Durham, NC) to visualize Doppler signal. Doppler measurements using GNRs were validated using a ...
Koyama Tomiyasu T Hokkaido University, 064-0821, Sapporo, Hokkaido N-1W-25, Japan, - - 2014
Forced retrograde perfusion through the venous system with arterial blood can provide adequate oxygen to peripheral tissues at rest through veno-capillary networks which is the basis for surgical restoration of blood flow by distal vein arterialization (DVA). To be successful such surgery requires disruption of valve leaflets in the veins, ...
Shiodera Taichiro T Corporate Research and Development Center, Toshiba Corporation, 1, Komukai-Toshiba-cho, Saiwai-ku, Kawasaki, 212-0001, Japan, - - 2013
The Time-Spatial Labeling Inversion Pulse (Time-SLIP) technique enables tracing of regional fluid flows without the use of contrast medium. The objective of this study is to quantify automatically slow and complex fluid flows using the Time-SLIP technique. Series images were acquired with a 1.5-T MRI scanner using the Time-SLIP technique ...
Mahadevia Riti R Northwestern University, Chicago, - - 2013
Aortic 3D blood flow was analyzed to investigate altered ascending aorta (AAo) hemodynamics in bicuspid aortic valve (BAV) patients and its association with differences in cusp fusion patterns (right-left, RL versus right-noncoronary, RN) and expression of aortopathy. 4D flow MRI measured in vivo 3D blood flow in the aorta of ...
Middione Matthew J MJ Department of Radiological Sciences, University of California, Los Angeles, Los Angeles, California, USA; Biomedical Physics Interdepartmental Program, University of California, Los Angeles, Los Angeles, California, - - 2013
To evaluate convex gradient optimization (CVX) for increased spatiotemporal resolution and improved accuracy for phase-contrast MRI (PC-MRI). A conventional flow-compensated and flow-encoded (FCFE) PC-MRI sequence was compared with a CVX PC-MRI sequence using numerical simulations, flow phantom experiments, and in vivo experiments. Flow measurements within the ascending aorta, main pulmonary ...
Semaan Edouard - - 2013
To provide a more complete characterization of aortic blood flow in patients following valve-sparing aortic root replacement (VSARR) compared with presurgical cohorts matched by tricuspid and bicuspid valve morphology, age and presurgical aorta size. Four-dimensional (4D) flow magnetic resonance imaging (MRI) was performed to analyse three-dimensional (3D) blood flow in ...
Bazan Ovandir - - 2013
In vitro hydrodynamic characterization of prosthetic heart valves provides important information regarding their operation, especially if performed by noninvasive techniques of anemometry. Once velocity profiles for each valve are provided, it is possible to compare them in terms of hydrodynamic performance. In this first experimental study using laser doppler anemometry ...
Hockley F A - - 2014
Riverine fish are subjected to heterogeneous flow velocities and turbulence and may use this to their advantage by selecting regions that balance energy expenditure for station holding while maximizing energy gain through feeding opportunities. This study investigated microhabitat selection by guppies Poecilia reticulata in terms of flow characteristics generated by ...
Qu Xiaofu X Division of Periodontology and Endodontology, Department of Oral Biology, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan; Dalian Stomatological Hospital, Changjiang Road 935, Shahekou District, Dalian 116021, - - 2014
Human pulpal blood flow (PBF) signals as measured by laser Doppler flowmeter (LDF) decrease with age. Although this decrease is considered to be due in part to slow blood flow, information regarding this velocity in humans has been lacking. The aims of the present study were to estimate the blood ...
von Knobelsdorff-Brenkenhoff Florian - - 2013
Aortic remodeling after aortic valve replacement (AVR) might be influenced by the postoperative blood flow pattern in the ascending aorta. This pilot study used flow-sensitive four-dimensional magnetic resonance imaging (4D-flow) to describe ascending aortic flow characteristics after various types of AVR. 4D-flow was acquired in 38 AVR patients (n=9 mechanical, ...
Sumikura Horohito - - 2013
We have used in-body tissue architecture technology to develop an autologous valved conduit with intact sinuses of Valsalva (biovalve). In this study, we fabricated three different forms of biovalves and evaluated their function in vitro using a mock circulation model to determine the optimal biovalve form for aortic valve replacement. ...
Mehregan Forough - - 2013
We propose a new approach to quantification of intracardiac vorticity based on conventional color Doppler images -Doppler vortography. Doppler vortography relies on the centrosymmetric properties of the vortices. Such properties induce particular symmetries in the Doppler flow data that can be exploited to describe the vortices quantitatively. For this purpose, ...
Marzban Caren - - 2013
Objectives- Transcranial Doppler sonography allows for the estimation of blood flow velocity, whose maximum value, especially at systole, is often of clinical interest. Given that observed values of flow velocity are subject to noise, a useful notion of "maximum" requires a criterion for separating the signal from the noise. All ...
Khodarahmi Iman - - 2013
To validate conventional phase-contrast MRI (PC-MRI) measurements of steady and pulsatile flows through stenotic phantoms with various degrees of narrowing at Reynolds numbers mimicking flows in the human iliac artery using stereoscopic particle image velocimetry (SPIV) as gold standard. A series of detailed experiments are reported for validation of MR ...
Jun Brian H - - 2013
A number of clinical, in vitro and computational studies have shown the potential for thromboembolic complications in bileaflet mechanical heart valves (BMHV), primarily due to the complex and unsteady flows in the valve hinges. These studies have focused on quantitative and qualitative parameters such as velocity magnitude, turbulent shear stresses, ...
Hansen Kristoffer Lindskov - - 2013
Conventional ultrasound (US) methods for blood velocity estimation only provide one-dimensional and angle-dependent velocity estimates; thus, the complexity of cardiac flow has been difficult to measure. To circumvent these limitations, the Transverse Oscillation (TO) vector flow method has been proposed. The vector flow method implemented on a commercial scanner provided ...
Vilkomerson David - - 2013
The signal backscattered by blood cells crossing a sample volume produces a Doppler power spectrum determined by the scatterers¿ velocity distribution. Because of intrinsic spectral broadening, the peak Doppler frequency observed does not correspond to the peak velocity in the flow. Several methods have been proposed for estimating the maximum ...
Weiss Nicolás - - 2013
We report on localized measurement of the longitudinal and transverse flow velocities in a colloidal suspension using optical coherence tomography. We present a model for the path-length resolved autocorrelation function including diffusion and flow, which we experimentally verify. For flow that is not perpendicular to the incident beam, the longitudinal ...
Guibert Romain - - 2013
3D computational fluid dynamics (CFD) in patient-specific geometries provides complementary insights to clinical imaging, to better understand how heart disease, and the side effects of treating heart disease, affect and are affected by hemodynamics. This information can be useful in treatment planning for designing artificial devices that are subject to ...
Adegbite Olusegun - - 2013
We have used a purely phase-encoded magnetic resonance imaging (MRI) technique, single-point ramped imaging with T1 enhancement (SPRITE), to investigate the steady, turbulent flow dynamics through a bileaflet mechanical heart valve (BMHV). We have measured in vitro the turbulent diffusivity and velocity downstream of the valve in two configurations (fully ...
Song Jisun L - - 2013
We present two novel microfluidic flow cells developed to provide reliable control of flow distributions and chemical gradients in biofilm studies. We developed a single-inlet microfluidic flow cell to support biofilm growth under a uniform velocity field, and a double-inlet flow cell to provide a very smooth transverse concentration gradient. ...
Parthasarathy S - - 2013
A breathing system is defined as an assembly of components, which delivers gases from the anesthesia machine to the patients' airways. When the components are arranged as a circle, it is termed a circle system. The flow of exhaled gases is unidirectional in the system. The system contains a component ...
Abadeh Aryan - - 2013
Movement of nuclei, mitochondria and vacuoles through hyphal trunks of Neurospora crassa were vector-mapped using fluorescent markers and GFP tags. The vectorial movements of all three were strongly correlated, indicating the central role of mass (bulk) flow in cytoplasm movements in N. crassa. Profiles of velocity versus distance from the ...
Mendes Pereira V - - 2013
BACKGROUND AND PURPOSE:Digital subtraction angiography is the reference standard technique to evaluate intracranial vascular anatomy and used on the endovascular treatment of vascular diseases. A dedicated optical flow-based algorithm was applied to DSA to measure arterial flow. The first quantification results of internal carotid artery flow validated with Doppler sonography ...
Bouwens Arno - - 2013
Optical coherence tomography (OCT) and optical coherence microscopy (OCM) allow the acquisition of quantitative three-dimensional axial flow by estimating the Doppler shift caused by moving scatterers. Measuring the velocity of red blood cells is currently the principal application of these methods. In many biological tissues, blood flow is often perpendicular ...
Luzi Aymeric - - 2013
The purpose of the study is to determine if femoral artery blood flow Doppler parameters can assess cardiac response to a fluid challenge (FC). We prospectively recorded in 52 critically ill ventilated patients' velocity time integral variation (%VTIf) and maximal systolic velocity variation (%Vfmax) derived from femoral Doppler analysis and ...
Muzzarelli S - - 2013
Bicuspid aortic valve (BAV) causes complex flow patterns in the ascending aorta (AAo), which may compromise the accuracy of flow measurement by phase-contrast magnetic resonance (PC-MR). Therefore, we aimed to assess and compare the accuracy of forward flow measurement in the AAo, where complex flow is more dominant in BAV ...
Middione Matthew J - - 2013
To investigate a novel phase-contrast MRI velocity-encoding technique for faster imaging and reduced chemical shift-induced phase errors. Velocity encoding with the slice select refocusing gradient achieves the target gradient moment by time shifting the refocusing gradient, which enables the use of the minimum in-phase echo time (TE) for faster imaging ...
Kojima Takanori - - 2013
Echo-Dynamography (EDG) is a smart visualization technique in echocardiography in which two-dimensional distribution of blood flow vectors in cardiovascular system is deduced by applying fluid dynamics theories into Doppler velocity datasets. Previous validation studies such as numerical simulation of free jet model or model circulation were too simple to reproduce ...
Zhong Liang - - 2013
In this study, hemodynamics in the normal and diseased left anterior descending (LAD) arterial trees were compared to estimate the effects of stenosis on the flow rate distribution, detailed flow field and wall shear stress (WSS) distributions on both transient and steady flow conditions. The anatomical model was reconstructed from ...
Zhang Yufeng - - 2013
A novel computer simulator to generate mixed Doppler ultrasound signals from the pulsatile blood flow and vessel wall with mild stenosis is presented in this paper. In-phase and quadrature Doppler blood flow signals are generated using cosine-superposed components modulated by a spectrogram estimated from velocity profile. Meanwhile,Doppler signals echoed from ...
Bissell Malenka M MM Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Oxford, United Kingdom. - - 2013
Ascending aortic dilation is important in bicuspid aortic valve (BAV) disease, with increased risk of aortic dissection. We used cardiovascular MR to understand the pathophysiology better by examining the links between 3-dimensional flow abnormalities, aortic function, and aortic dilation. A total of 142 subjects underwent cardiovascular MR (mean age, 40 ...
Richy Julien - - 2013
Duplex ultrasonography is a mode of medical ultrasonography that allows one to visualize, at the same time, the inner structure of the body (B-mode) and the blood flow at a particular point in the body (Doppler mode). This mode requires a strategy for alternating B-mode and flow emissions. Traditional strategies ...
Lorenz R - - 2013
PURPOSE: Changes in aortic geometry or presence of aortic valve (AoV) disease can result in substantially altered aortic hemodynamics. Dilatation of the ascending aorta or AoV abnormalities can result in an increase in helical flow. METHODS: 4D flow magnetic resonance imaging was used to test the feasibility of quantitative helicity ...
Yang Xin - - 2013
Preclinical ultrasound scanners are used to measure blood flow in small animals, but the potential errors in blood velocity measurements have not been quantified. This investigation rectifies this omission through the design and use of phantoms and evaluation of measurement errors for a preclinical ultrasound system (Vevo 770, Visualsonics, Toronto, ...
Song Wei - - 2013
We present a methodology to measure absolute flow velocity using laser-scanning photoacoustic microscopy. To obtain the Doppler angle, the angle between ultrasonic detection axis and flow direction, we extracted the distances between the transducer and three adjacent scanning points along the flow and repeatedly applied the law of cosines. To ...
Holten Vivian - - 2013
Optic flow simulating self-motion through the environment can induce postural adjustments in observers. Some studies investigating this phenomenon have used optic flow patterns increasing in speed from center to periphery, whereas others used optic flow patterns with a constant speed. However, altering the speed gradient of an optic flow stimulus ...
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