scholarly journals Fluid-induced wall shear stress in anthropomorphic brain aneurysm models: MR phase-contrast study at 3 T

2007 ◽  
Vol 25 (6) ◽  
pp. 1120-1130 ◽  
Author(s):  
Sinyeob Ahn ◽  
Dongsuk Shin ◽  
Satoshi Tateshima ◽  
Kazuo Tanishita ◽  
Fernando Vinuela ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Phase Contrast ◽  
Contrast Study ◽  
Brain Aneurysm ◽  
Wall Shear

scholarly journals Wall Shear Stress Measurement Using Phase Contrast Magnetic Resonance Imaging with Phase Contrast Magnetic Resonance Angiography in Arteriovenous Polytetrafluoroethylene Grafts

Angiology ◽  
2009 ◽  
Vol 60 (4) ◽  
pp. 441-447 ◽  
Author(s):  
Sanjay Misra ◽  
Alex A. Fu ◽  
Khamal D. Misra ◽  
James F. Glockner ◽  
Debabrata Mukhopadhyay
Keyword(s):  
Magnetic Resonance Imaging ◽  
Shear Stress ◽  
Magnetic Resonance ◽  
Wall Shear Stress ◽  
Phase Contrast ◽  
Resonance Imaging ◽  
Phase Contrast Magnetic Resonance ◽  
Venous Stenosis ◽  
Contrast Magnetic Resonance ◽  
Wall Shear

Purpose The purpose of the present article was to determine the changes in luminal vessel area, blood flow, and wall shear stress in both the inflow artery and the venous stenosis of arteriovenous polytetrafluoroethylene (PTFE) grafts. Methods and materials Polytetrafluoroethylene grafts were placed from the carotid artery to the ipsilateral jugular vein in 8 castrated juvenile male pigs. Contrast-enhanced magnetic resonance angiography (MRA) with cine phase-contrast magnetic resonance imaging (MRI) was performed 2 weeks after graft placement. Results The mean wall shear stress at the venous stenosis was 4 times higher than the control vein, while the inflow artery was only 2-fold higher. By day 14, venous stenosis had formed, which was characterized by narrowed area and elevated blood flow. Conclusion By day 14, there is venous stenosis formation in porcine arteriovenous PTFE grafts with increased shear stress with decreased area when compared to control vein.

Volumetric arterial wall shear stress calculation based on cine phase contrast MRI

2014 ◽  
Vol 41 (2) ◽  
pp. 505-516 ◽  
Author(s):  
Wouter V. Potters ◽  
Pim van Ooij ◽  
Henk Marquering ◽  
Ed vanBavel ◽  
Aart J. Nederveen
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Phase Contrast ◽  
Arterial Wall ◽  
Phase Contrast Mri ◽  
Stress Calculation ◽  
Wall Shear ◽  
Cine Phase Contrast

Allometric scaling of wall shear stress from mice to humans: quantification using cine phase-contrast MRI and computational fluid dynamics

2006 ◽  
Vol 291 (4) ◽  
pp. H1700-H1708 ◽  
Author(s):  
Joan M. Greve ◽  
Andrea S. Les ◽  
Beverly T. Tang ◽  
Mary T. Draney Blomme ◽  
Nathan M. Wilson ◽  
...  
Keyword(s):  
Shear Stress ◽  
Magnetic Resonance ◽  
Wall Shear Stress ◽  
Cardiovascular System ◽  
Phase Contrast ◽  
Scaling Laws ◽  
Allometric Scaling ◽  
Scaling Exponent ◽  
Infrarenal Aorta ◽  
Wall Shear

Allometric scaling laws relate structure or function between species of vastly different sizes. They have rarely been derived for hemodynamic parameters known to affect the cardiovascular system, e.g., wall shear stress (WSS). This work describes noninvasive methods to quantify and determine a scaling law for WSS. Geometry and blood flow velocities in the infrarenal aorta of mice and rats under isoflurane anesthesia were quantified using two-dimensional magnetic resonance angiography and phase-contrast magnetic resonance imaging at 4.7 tesla. Three-dimensional models constructed from anatomic data were discretized and used for computational fluid dynamic simulations using phase-contrast velocity imaging data as inlet boundary conditions. WSS was calculated along the infrarenal aorta and compared between species to formulate an allometric equation for WSS. Mean WSS along the infrarenal aorta was significantly greater in mice and rats compared with humans (87.6, 70.5, and 4.8 dyn/cm2, P < 0.01), and a scaling exponent of −0.38 ( R2 = 0.92) was determined. Manipulation of the murine genome has made small animal models standard surrogates for better understanding the healthy and diseased human cardiovascular system. It has therefore become increasingly important to understand how results scale from mouse to human. This noninvasive methodology provides the opportunity to serially quantify changes in WSS during disease progression and/or therapeutic intervention.

Impact of Stents and Flow Diverters on Hemodynamics in Idealized Aneurysm Models

2011 ◽  
Vol 133 (7) ◽  
Author(s):  
Santhosh Seshadhri ◽  
Gábor Janiga ◽  
Oliver Beuing ◽  
Martin Skalej ◽  
Dominique Thévenin
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Residence Time ◽  
Exchange Flow ◽  
Invasive Treatment ◽  
Mean Velocity ◽  
Brain Aneurysm ◽  
Geometrical Properties ◽  
Wall Shear ◽  
Flow Diverters

Cerebral aneurysms constitute a major medical challenge as treatment options are limited and often associated with high risks. Statistically, up to 3% of patients with a brain aneurysm may suffer from bleeding for each year of life. Eight percent of all strokes are caused by ruptured aneurysms. In order to prevent this rupture, endovascular stenting using so called flow diverters is increasingly being regarded as an alternative to the established coil occlusion method in minimally invasive treatment. Covering the neck of an aneurysm with a flow diverter has the potential to alter the hemodynamics in such a way as to induce thrombosis within the aneurysm sac, stopping its further growth, preventing its rupture and possibly leading to complete resorption. In the present study the influence of different flow diverters is quantified considering idealized patient configurations, with a spherical sidewall aneurysm placed on either a straight or a curved parent vessel. All important hemodynamic parameters (exchange flow rate, velocity, and wall shear stress) are determined in a quantitative and accurate manner using computational fluid dynamics when varying the key geometrical properties of the aneurysm. All simulations are carried out using an incompressible, Newtonian fluid with steady conditions. As a whole, 72 different cases have been considered in this systematic study. In this manner, it becomes possible to compare the efficiency of different stents and flow diverters as a function of wire density and thickness. The results show that the intra-aneurysmal flow velocity, wall shear stress, mean velocity, and vortex topology can be considerably modified thanks to insertion of a suitable implant. Intra-aneurysmal residence time is found to increase rapidly with decreasing stent porosity. Of the three different implants considered in this study, the one with the highest wire density shows the highest increase of intra-aneurysmal residence time for both the straight and the curved parent vessels. The best hemodynamic modifications are always obtained for a small aneurysm diameter.

Quantification of wall shear stress using a finite-element method in multidimensional phase-contrast MR data of the thoracic aorta

2015 ◽  
Vol 48 (10) ◽  
pp. 1817-1827 ◽  
Author(s):  
Julio Sotelo ◽  
Jesús Urbina ◽  
Israel Valverde ◽  
Cristian Tejos ◽  
Pablo Irarrázaval ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Thoracic Aorta ◽  
Phase Contrast ◽  
Wall Shear ◽  
Element Method

Wall shear stress estimated with phase contrast MRI in an in vitro and in vivo intracranial aneurysm

2013 ◽  
Vol 38 (4) ◽  
pp. 876-884 ◽  
Author(s):  
Pim van Ooij ◽  
Wouter V. Potters ◽  
Annetje Guédon ◽  
Joppe J. Schneiders ◽  
Henk A. Marquering ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Intracranial Aneurysm ◽  
Phase Contrast ◽  
Phase Contrast Mri ◽  
Wall Shear
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