Pediatric Transthoracic Cardiac Vector Flow Imaging – A Preliminary Pictorial Study

Abstract Purpose Conventional pediatric echocardiography is crucial for diagnosing congenital heart disease (CHD), but the technique is impaired by angle dependency. Vector flow imaging (VFI) is an angle-independent noninvasive ultrasound alternative for blood flow assessment and can assess complex flow patterns not visible on conventional Doppler ultrasound. Materials and Methods 12 healthy newborns and 3 infants with CHD were examined with transthoracic cardiac VFI using a conventional ultrasound scanner and a linear array. Results VFI examinations revealed common cardiac flow patterns among the healthy newborns, and flow changes among the infants with CHD not previously reported with conventional echocardiography. Conclusion For assessment of cardiac flow in the normal and diseased pediatric heart, VFI may provide additional information compared to conventional echocardiography and become a useful diagnostic tool.

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Ultrasound Vector Flow Imaging – could be a new tool in evaluation of arteriovenous fistulas for hemodialysis?

The Journal of Vascular Access ◽

10.5301/jva.5000721 ◽

2017 ◽

Vol 18 (4) ◽

pp. 284-289 ◽

Cited By ~ 8

Author(s):

Ilaria Fiorina ◽

Maria Vittoria Raciti ◽

Alfredo Goddi ◽

Vito Cantisani ◽

Chandra Bortolotto ◽

...

Keyword(s):

Venous Aneurysm ◽

Flow Imaging ◽

Angular Deviation ◽

Complex Flow ◽

Mean Velocity ◽

Ultrasound Technique ◽

Arteriovenous Fistulas ◽

The Mean ◽

Vessel Walls ◽

Ultrasound Scanner

Introduction We report the use of a new ultrasound technique to evaluate the axial and lateral components of a complex flow in the arteriovenous fistula (AVF). Vector Flow Imaging (VFI) allows to identify different components of the flow in every direction, even orthogonal to the flow streamline, represented by many single vectors. VFI could help to identify flow alterations in AVF, probably responsible for its malfunction. Methods From February to June 2016, 14 consecutive patients with upper-limb AVF were examined with a Resona 7 (Mindray, Shenzhen, China) ultrasound scanner equipped with VFI. An analysis of mean velocity, angular direction and mean number of vectors impacting the vessel wall was carried out. We also identified main flow patterns present in the arterial side, into the venous aneurysm and in correspondence of significant stenosis. Results A disturbed flow with the presence of vectors directed against the vessel walls was found in 9/14 patients (64.28%): in correspondence of the iuxta-anastomotic venous side (4/9; 44.4%), into the venous aneurysmal tracts (3/9; 33.3%) and in concomitance of stenosis (2/9; 22.2%). The mean velocity of the vectors was around 20-25 cm/s, except in presence of stenosis, where the velocities were much higher (45-50 cm/s). The vectors directed against the vessel walls presented high angle attack (from 45° to 90°, with a median angular deviation 65°). Conclusions VFI was confirmed to be an innovative and intuitive imaging technology to study the flow complexity in the arteriovenous fistulas.

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Contrast-Enhanced Ultrasound (CEUS) in Non-Traumatic Abdominal Emergencies

Ultrasound International Open ◽

10.1055/a-1347-5875 ◽

2020 ◽

Vol 06 (03) ◽

pp. E76-E86

Author(s):

Diletta Cozzi ◽

Simone Agostini ◽

Elena Bertelli ◽

Michele Galluzzo ◽

Emanuela Papa ◽

...

Keyword(s):

Computed Tomography ◽

Ultrasound Imaging ◽

Acute Inflammation ◽

Emergency Setting ◽

Contrast Enhanced Ultrasound ◽

First Line ◽

Additional Information ◽

Contrast Enhanced ◽

Conventional Ultrasound ◽

Abdominal Emergencies

AbstractConventional ultrasound imaging (US) is the first-line investigation in acute non-traumatic abdominal emergencies, but sometimes it needs further examinations, such as computed tomography (CT), to reach a certain diagnosis. Contrast-enhanced ultrasound (CEUS), through injection of contrast medium, may provide the radiologist with additional information that could not be investigated with baseline US. It could help reach a diagnosis and rapidly determine the proper therapy in an emergency setting. The purpose of this review is to explain and illustrate the various possibilities and limitations of CEUS in acute non-traumatic abdominal diseases, in particular acute inflammation, parenchymal infarcts, and hemorrhages.

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Stability Analysis of Hydropower Stations With Complex Flow Patterns in the Tailrace Tunnel

Volume 2, Fora: Cavitation and Multiphase Flow; Fluid Measurements and Instrumentation; Microfluidics; Multiphase Flows: Work in Progress ◽

10.1115/fedsm2013-16617 ◽

2013 ◽

Cited By ~ 1

Author(s):

Jianxu Zhou ◽

Fulin Cai ◽

Ming Hu

Keyword(s):

Free Surface ◽

Stability Analysis ◽

Flow Patterns ◽

Normal Operation ◽

Complex Flow ◽

Diversion Tunnel ◽

Implicit Model ◽

Special Cases ◽

Tailrace Tunnel ◽

Hydropower Stations

For some special tailrace tunnels in the hydropower stations, including the changing top-altitude tailrace tunnel and the tailrace tunnel with downstream reused flat-ceiling diversion tunnel, during normal operation and hydraulic transients, the flow patterns inside are relatively complex mainly including the free-surface pressurized flow and partial free flow if the tail water level is lower than the top elevation of tunnel’s outlet. These complex flow patterns have obvious effect on system’s stability, and can not be simulated accurately by the traditional models. Therefore, a characteristic implicit model is introduced to simulate these complex flow patterns for further stability analysis. In some special cases, the characteristic implicit model also fails to completely simulate the mixed free-surface pressurized flow in the flat-ceiling tailrace tunnel. A new method is presented based on both experimental research and numerical simulation, and then, system’s stability is analyzed by compared with traditional ordinary boundary condition. The results indicate that, with different simulation models for the complex water flow in the tailrace tunnel, system’s dynamic characteristic can be actually revealed with the consideration of the effect of complex flow patterns in the tailrace tunnel on system’s stability and regulation performance.

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Characterization of complex flow patterns in the ascending aorta in patients with aortic regurgitation using conventional phase-contrast velocity MRI

The International Journal of Cardiovascular Imaging ◽

10.1007/s10554-017-1239-3 ◽

2017 ◽

Vol 34 (3) ◽

pp. 419-429 ◽

Cited By ~ 2

Author(s):

Odd Bech-Hanssen ◽

Frida Svensson ◽

Christian L. Polte ◽

Åse A. Johnsson ◽

Sinsia A. Gao ◽

...

Keyword(s):

Aortic Regurgitation ◽

Phase Contrast ◽

Flow Patterns ◽

Ascending Aorta ◽

Complex Flow

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Computational Study of Gas Turbine Blade Cooling Channel

2010 14th International Heat Transfer Conference, Volume 5 ◽

10.1115/ihtc14-22920 ◽

2010 ◽

Cited By ~ 3

Author(s):

R. S. Amano ◽

Krishna Guntur ◽

Jose Martinez Lucci

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Gas Turbine ◽

Turbulence Models ◽

Flow Patterns ◽

Higher Order ◽

Secondary Flows ◽

Complex Flow ◽

Cooling Performance ◽

Cooling Channels

It has been a common practice to use cooling passages in gas turbine blade in order to keep the blade temperatures within the operating range. Insufficiently cooled blades are subject to oxidation, to cause creep rupture, and even to cause melting of the material. To design better cooling passages, better understanding of the flow patterns within the complicated flow channels is essential. The interactions between secondary flows and separation lead to very complex flow patterns. To accurately simulate these flows and heat transfer, both refined turbulence models and higher-order numerical schemes are indispensable for turbine designers to improve the cooling performance. Power output and the efficiency of turbine are completely related to gas firing temperature from chamber. The increment of gas firing temperature is limited by the blade material properties. Advancements in the cooling technology resulted in high firing temperatures with acceptable material temperatures. To better design the cooling channels and to improve the heat transfer, many researchers are studying the flow patterns inside the cooling channels both experimentally and computationally. In this paper, the authors present the performance of three turbulence models using TEACH software code in comparison with the experimental values. To test the performance, a square duct with rectangular ribs oriented at 90° and 45° degree and placed at regular intervals. The channel also has bleed holes. The normalized Nusselt number obtained from simulation are validated with that of experiment. The Reynolds number is set at 10,000 for both the simulation and experiment. The interactions between secondary flows and separation lead to very complex flow patterns. To accurately simulate these flows and heat transfer, both refined turbulence models and higher-order numerical schemes are indispensable for turbine designers to improve the cooling performance. The three-dimensional turbulent flows and heat transfer are numerically studied by using several different turbulence models, such as non-linear low-Reynolds number k-omega and Reynolds Stress (RSM) models. In k-omega model the cubic terms are included to represent the effects of extra strain-rates such as streamline curvature and three-dimensionality on both turbulence normal and shear stresses. The finite volume difference method incorporated with the higher-order bounded interpolation scheme has been employed in the present study. The outcome of this study will help determine the best suitable turbulence model for future studies.

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