Effects of Morphological Variations on Hemodynamic Parameters in the Middle Cerebral Artery: A study conducted through Computational Fluid Dynamics
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Examensarbete på kandidatnivå
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Publicerad
2022
Författare
Malmsköld, Pontus
Odbratt, Johanna
Peyvandi, Ehsan
Åkesson, Louise
Modellbyggare
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Sammanfattning
Stroke is a large contributor to deaths around the world. One common cause of stroke is an Intracranial
Aneurysm, which causes the wall of the artery to expand and potentially rupture leading to
hemorrhage in the brain. The formation and rupture of both aneurysms as well as other contributors
to stroke, are tied to specific hemodynamic properties such as wall shear stress. This paper aims to
investigate the differences in wall shear stress in different patients in a bifurcating part of the cerebral
vascular system that is prone to developing stroke; the middle cerebral artery. This in order to
see how morphological differences between patients affect the hemodynamic parameters such as wall
shear stress. This was done using an in silico method within Computational fluid dynamics called
the Lattice Boltzmann method for two different patients. The Herschel Bulkley model was used in
order to properly model the non-Newtonian flow of blood. The data for the two patients were provided
though open-source MRI scans where the vascular system was extracted through thresholding.
The results of simulating the flow for both patients showed that the mean shear rate is quite similar
for the two patients, with some significant differences in local shear rate. These differences were
attributed to the bifurcation angles of the arteries, where the patient with the largest bifurcation
angle had the highest local shear rate both in and after the bifurcation. A higher shear rate implies
a higher wall shear stress, which resulted in the fact that a larger bifurcation angle seems to give
rise to a higher wall shear stress. Hence, the risk of developing Intracranial Aneurysms and other
conditions leading to stroke in the middle cerebral artery, seems to be higher when the bifurcation
angle is large.