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2 edition of Modeling ultrasound imaging of red blood cell aggregation in shear flow. found in the catalog.

Modeling ultrasound imaging of red blood cell aggregation in shear flow.

Brian Lim

Modeling ultrasound imaging of red blood cell aggregation in shear flow.

by Brian Lim

  • 320 Want to read
  • 24 Currently reading

Published .
Written in English


The Physical Object
Pagination116 leaves.
Number of Pages116
ID Numbers
Open LibraryOL18876172M
ISBN 10061241213X

RBCs was obtained by varying both the flow shear rate, and the strength of interactions between the red cells. Modeling the exact mechanisms of RBC aggregation is outside the scope of this paper. To our knowledge, it is the first attempt to model polydispersity in . Power Doppler ultrasound scan imaging of the level of red blood cell aggregation: An in vitro study Power Doppler ultrasound scan (PDU) is an imaging method that displays the power of the Doppler scan blood flow signal. 1 This technique is.

The widely accepted model for RBC aggregation is the depletion model The presence of macromolecules like fibrinogen and.2 macroglobulin can enhance red blood cell aggregation in autologous plasma. Rouleaux formation can also be induced by suspending RBCs in physiological solutions of macromolecules like dextran (DEX). A major application of diagnostic ultrasound is the visualization and measurement of hemodynamic flow in the major vessels, organs, and heart. The weak ultrasound scattering from flowing red blood cells causes a Doppler frequency shift that can track the hemodynamics of flow.

The ultrasound backscattered signal was computed with a linear model that considers the characteristics of the ultrasound system and tissue acoustic properties. The tissue scattering properties were related to the position and shape of the red blood cells (RBCs). A 2D microrheological model simulated the RBC dynamics in a Couette shear flow. Introduction. Red blood cell (RBC) aggregation is a normal and reversible phenomenon influencing blood flow throughout the circulation. The basic structure of RBC aggregates (or “rouleaux”) is an alignment of several cells, very similar to a “stack of coins” [].RBC aggregates are likely to form in venules and veins, where flow shear forces are low, and they are .


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Modeling ultrasound imaging of red blood cell aggregation in shear flow by Brian Lim Download PDF EPUB FB2

Modeling Ultrasound haging of Red Blood Ce11 Aggregation in Shear Flow Brian Lim, Ph.D. Institute of Biomedical Engineering Department of Electrical and Computer Engineering, University of Toronto The primary focus of this thesis is to gain an understanding of the effects of red blood Author: Brian Lim.

Purpose: The purpose of this study was to evaluate the effect of the shear rate on red blood cell (RBC) aggregation with power Doppler ultrasound scanning (PDU), pulsed-wave Doppler scanning, and color Doppler flow s: Equine and porcine blood were circulated with a steady flow in a phantom with a diameter of mm.

The color Doppler flow imaging. Many in vitro and in vivo experiments have been performed to demonstrate the utility of this approach for characterizing the eye,1, 2 liver,3 kidney,4 prostate,5 and breast.6 Recently, the frequency dependence of the ultrasound (US) backscatter coefficient was studied to assess the level of red blood cell (RBC) aggregation.7Cited by: This chapter provides a review of the last 15 years on the use of quantitative ultrasound (QUS) techniques to characterize red blood cell (RBC) aggregation (i.e., aggregate size.

The frequency dependence of the ultrasonicbackscatteringcoefficient (BSC) was studied to assess the level of red blood cell (RBC) aggregation. Three monoelement focused wideband transducerswere used to insonify porcine blood sheared in a Couette flowfrom 9to30MHz. A high shear rate was first applied to promote by: Although the shear-dependent and reversible phenomenon of red blood cell (RBC) aggregation has been studied for decades, its role as a determinant of in vivo blood flow.

A simulation model has been developed for red blood cell (RBC) aggregation in shear flow. It is based on a description of the collision rates of RBC, the probability of particles sticking together, and the breakage of aggregates by shear forces. This chapter provides a review of the last 15 years on the use of quantitative ultrasound (QUS) techniques to characterize red blood cell (RBC) aggregation (i.e., aggregate size, structure and packing organization).

The paper focuses on studies aimed at explaining factors affecting the frequency dependent backscatter coefficient (BSC).Cited by: 6. Furthermore, there is a growing interest to characterize blood scattering at higher frequencies for high-resolution imaging.

To describe the effect of red cell aggregation, it is thus preferable to refer to the structure factor, which describes the frequency and the orientational dependence of the backscattered power.

Ultrasound imaging, which can measure flow and is sensitive to in vivoand in vitroRBC aggregation, was used to detail local flow and RBC aggregation. Our findings in an animal model support the hypothesis that local characterisation of aggregation could be of predictive value in patients at risk for DVT.

The frequency dependence of the ultrasound signal backscattered by blood in shear flow was studied using a simulation model. The ultrasound backscattered signal was computed with a linear model that considers the characteristics of the ultrasound system and tissue acoustic properties.

The tissue scattering properties were related to the position and shape of the red blood cells. Tissue characterization using ultrasound (US) scattering allows extraction of relevant cellular biophysical information noninvasively. Characterization of the level of red blood cell (RBC) aggregation is one of the proposed application.

In the current paper, it is hypothesized that the microstructure of the RBCs is a main determinant of the US backscattered power. However, recent evidence suggests that non-Newtonian behavior is relevant, probably because of the deformation of red cells rather than aggregation.

Hence, blood flow models used with arterial ultrasound should account for red cell deformation and the shear thinning characteristics of blood that this produces. Photoacoustic ultrasound spectroscopy for assessing red blood cell aggregation and oxygenation Eno Hysi, aRatan K.

Saha,b and Michael C. Kolios aRyerson University, Department of Physics, Victoria Street, Toronto, Ontario, M5B 2K3 Canada bSaha Institute of Nuclear Physics, Applied Material Science Division, 1/AF Bidhannagar, Kolkata, India.

To develop methods for noninvasively and quantitatively measuring blood glucose levels. In the present study, we evaluated the degree of red blood cell (RBC) aggregation at a low shear rate robustly by introducing two new parameters determined from changes in the scattering power spectrum of the echoes from the intravascular lumen before and after cessation of blood flow.

Red blood cell (RBC) aggregation exists in the normal blood circulation and is abnormally increased in patients with degenerative diseases, acute and chronic infections. The process of RBC aggregation is reversible and governed by the shear forces of the flow.

Schmid-Schönbein H, Volger E. Red-cell aggregation and red-cell deformability in diabetes. Diabetes. ; 25 (2 Suppl)– Shehada RE, Cobbold RS, Mo LY.

Aggregation effects in whole blood: influence of time and shear rate measured using ultrasound. Biorheology. Jan-Feb; 31 (1)– Red blood cells (RBCs) aggregate in the presence of increased plasma fibrinogen and low shear forces during blood flow.

RBC aggregation has been observed in deep vein thrombosis, sepsis and diabetes. We propose using photoacoustics (PA) as a non-invasive imaging modality to detect RBC aggregation.

The theoretical and experimental. The tissue function was described by the position and the shape of the red blood cells (RBCs). The effect of the flow on the spatial organization of aggregating RBCs was simulated with a 2D model.

It is an iterative model that considers the effect of the flow and the adhesive and repulsive forces acting on each RBC. Red blood cells are known to form aggregates in the form of rouleaux.

This aggregation process is believed to be reversible, but there is still no full understanding on the binding mechanism. Red blood cells (RBCs) aggregate in the presence of increased plasma fibrinogen and low shear forces during blood flow.

RBC aggregation has been observed in .However, shear stress drives Couette flow, whereas pressure gradients drive Poiseuille flow and physiological blood flow as well. Pressure gradients may cause variations in the kinetics and aggregation of RBCs in blood flow. The shear rate of arterial blood flow inherently changes radially in the blood vessel and temporally during a cardiac cycle.A system-based model is proposed to describe and simulate the ultrasound signal backscattered by red blood cells (RBCs).

The model is that of a space-invariant linear system that takes into consideration important biological tissue stochastic scattering properties as well as the characteristics of the ultrasound system.

The formation of the ultrasound signal is .