Biomedical Engineering Reference
In-Depth Information
Fig. 8.47
Finite element meshes for the computational model showing different cut-surfaces. (
a
)
Mesh for the solid domain showing the position of a bifurcation-cut (
B-cut
) surface; (
b
) A longi-
tudinal-cut (
L-cut
) surface showing the lipid core and thin plaque cap; (
c
) Location of the L-cut
surface. (Image adapted from Yang et al. 2010)
ing sliced planes showing bifurcation and another sliced plane showing the lipid
core.
Flow shear stress distributions from both models were similar on the two planes,
since the no-component modelling simplification does not change the fluid domain
and its effect on the overall plaque deformation. However there is a difference
in the plaque wall stress distribution on the longitudinal which contained a lipid
pool. Yang et al. (2010) suggests that the errors introduced by the no-component
approach depend heavily on the number of components, component size and the
total “thin-cap” lumen area.
A further example studying patient specific 3D FSI models of carotid plaques is
by Huang et al. (2009). Their work presented a method to quantify human carotid
artery axial and inner circumferential shrinkages, based in vivo MRI data. However
for this example we review the plaque stress, strain, flow velocity, and shear stress
behaviour results. Scans of ten patients were used to reconstruct the carotid bifurca-
tion using the CASCADE software while the computational mesh used the ADINA
software (Fig.
8.47
). The artery wall and plaque components were assumed hyper-
elastic, isotropic, incompressible and homogeneous. The vessel wall and plaque
component material properties used the 3D nonlinear modified Mooney-Rivlin (M-
R) model. Blood flow was assumed laminar, Newtonian, viscous and incompress-
ible and the equations were discretised to the Arbitrary-Lagrangian-Eulerian (ALE)
formulation.
Results showing the maximum principal stress (Stress-P1) and maximum
principal strain (Strain-P1) distributions, flow velocity, pressure and maximum-
shear-stress (MSS) on two sagittal cut surfaces for one case are shown in Fig.
8.48
.
On the B-cut surface, maximum Stress-P1 value was found where the vessel wall
was thin and a minimum value occurred at the lipid pool. Figure
8.48b
shows that
maximum Strain-P1 was located at plaque cap. Figure
8.48c
-
f
give plots of struc-
ture and flow features on L-cut surface which shows lipid pool and cap thickness.
The distribution of Stress-P1 shows a maximum value located at the lipid cap po-
sition. Flow velocity is higher at the stenosis narrowing of internal carotid artery
(ICA). A maximum value of Maximum-Shear Stress occurred at the plaque throat
where narrowing occurs.
Search WWH ::
Custom Search