Biomedical Engineering Reference
In-Depth Information
To make computational models relevant and useful for clinical applications,
it is necessary to ensure their accuracy in capturing important flow fea-
tures. Some researchers have conducted numerical simulations of the flow in
intracranial aneurysms using patient-specific geometries obtained from med-
ical imaging data. Steinman et al. [32] presented image-based computational
simulations of the flow dynamics in a giant anatomically realistic, human
intracranial aneurysm assuming rigid walls. Their analysis revealed high-speed
flow entering the aneurysm at the proximal and distal ends of the neck, pro-
moting the formation of persistent and transient vortices within the aneurysm
sac. Stuhne and Steinman [44] conducted a numerical study to analyze the
WSS distribution and flow streamlines near the neck of a stented basilar rigid
side-wall aneurysm. The numerical simulations were performed assuming con-
stant pressure at the outflow boundary of the model and specifying either
steady or pulsatile flow at the inlet. Shojima et al. [45] performed a numerical
study in middle cerebral artery (MCA) aneurysms to quantify the magnitude
and role of WSS on cerebral aneurysm with the assumption of Newtonian
fluid property for blood and the rigid wall property for the parent vessel and
the aneurysm. Their results showed that the maximum WSS occurred near
the neck of the aneurysm, not in its tip or dome. Appanaboyina et al. [31]
conducted a CFD analysis of stented intracranial aneurysms using adaptive
embedded unstructured grids. Their results showed that this methodology can
be used to model patient-specific anatomies with different stents and makes
it possible to explore the effect of different stent designs. Rayz et al. [46] con-
ducted a numerical study to compute the velocity field and WSSs in patient-
specific geometries. Flow velocities in the arteries proximal to the aneurysm
obtained by MRI scanning were used to specify the inlet flow conditions for
each patient. Their results showed a good agreement between the flow fields
measured
in vivo
using the in-plane MRV technique and those computed with
CFD simulations.
Computational fluid dynamic of coil embolization has been rarely
attempted because it is di
cult to describe numerically the irregularly shaped
coil. A few attempts have been made to simulate aneurysm coiling using differ-
ent methods. Byun and Rhee [47] used computational methods to analyze the
flow fields in partially blocked aneurysm models. These authors modeled the
coils as a small solid sphere placed at different locations within the aneurys-
mal sac. They showed that the intraaneurysmal blood flow motion was smaller
when the sphere was placed at the neck compared to when it was placed in the
dome of the aneurysm. Groden et al. [48] studied three-dimensional pulsatile
flow simulation before and after endovascular coil embolization of a cerebral
aneurysm using
in vivo
data obtained by computerized tomographic angiogra-
phy (CTA). In their CFD model, these authors used cube-shaped cells to rep-
resent the coils. Their results showed that a complete cessation of flow through
the aneurysm neck was achieved with a 20% filling of blocks. The cube-shaped
cells are a rough approximation to model the random tortuosity of the coil.
Cha et al. [49] conducted a numerical study to analyze the interaction of coils
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