3d fe analysis iof intracranial aneurysm

An aneurysm is defined as: A cardiovascular disease characterized by a saclike widening of an artery resulting from weakening of the artery wall

Intracranial aneurysms(ICA) have a prevalence of 2%-6.5%

Common places for ICAs are the cerebral artery, internal carotid artery, basilar artery, and the anterior communicating artery

Cerebral blood pressure is autoregulated Currently doctors use diameter as a measure of severity

1. http://wordnetweb.princeton.edu/perl/webwn?s=aneurysm 2. Chien A, Castro MA, Tateshima S, et al. Quantitative hemodynamic analysis of brain aneurysms at different locations. AJNR Am J Neuroradiol. 2009;30:1507‐1512.

Relate acute increases in blood pressure with mechanical stress and strain values within an intracranial aneurysm.

http://en.wikipedia.org/wiki/File:Circle_of_Willis_en.svg

Einc: .65MPa 12.2MPa 12.2MPa

ν=.499 Shell Elements, thickness=.086mm Pressure Control-122 mm Hg Aerobic exercise-163 mm Hg Valsalva-250 mm Hg

Elastic/Isotropic materialMiddle cerebral blood pressure during a Valsalva manouver in the standing position, Frank Pott, et al., J Applied PhysiologyPhysical exercise increases middle cerebral artery blood flow velocity, Gunnar Hellstrom, Nils Gunnar Wahlgren, Neurosurgery Rev.The static elastic properties of the arterial wall, D. H. Bergel, J. Physiology

Obtain aneurysm as .dat file and convert to .stl Load into IA-FEMes 1.0 Create block structure Mesh seed-> length=.25 Mesh-> shell elements Add ELSETS & BCs Export to ABAQUS Manually enter pressure values Run ABAQUS and complete post processing

Valsalva

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pa Max VonMises

max at 3407

Lowering maximum stress threshold shows greater detail in values which further deviate from the maxima

Regions of high stress have a strong correlation with regions of greater contour

Valsalva

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max at 3407

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Max in plane stress

max at 3407

Risk of intracranial aneurysm rupture varies greatly from patient to patient. There is not enough information known to use stress/strain as an indication for rupture. However, there tends to be a concentration of stress near areas of large contour.

Diameter of the aneurysm is likely the simplest/most effective method of assessing aneurysm risk of rupture in a clinical setting