Biomedical Engineering Reference
In-Depth Information
Fig. 19.7
Interstitial fluid
excess pressure
p
IR
(
left
)and
norm of the solid
displacements
|
u
S
|
at varying
permeabilities. Therein,
K
I
indicates the order of
magnitude of the spatial
varying Darcy permeability
Fig. 19.8
Left
: Geometrical
preparation of the cerebral
hemisphere for the
finite-element meshing.
Right
: Numerical simulation
results of a CED process,
showing the spatial
therapeutic agent distribution
19.3.2 Investigations on a Human Brain Hemisphere
For the sake of clarity, the simulation of a CED process was evaluated and discussed
on a 2D brain slice. But since all formulations are derived in three dimensions, re-
alistic geometries (e.g., of the human brain hemisphere) can be investigated. There-
fore, a standard human brain (commercially available at
www.anatomium.com
)is
used to survey the general physical behavior. The geometry was first adapted using
the CAD software R
HINOCEROS
to prepare the cerebral hemisphere for the spa-
tial discretization, cf. Fig.
19.8
(left). Afterwards, the geometry was exported into
the mesh generation toolkit C
UBIT
and spatial discretized using tetrahedral Taylor-
Hood elements. In the vicinity of the incorporated catheter, a finer grid was chosen.
Boundary conditions and material parameters are applied according to Sect.
19.3.1
.
Realized numerical simulations show the 3D distribution front of therapeutic agents
in the 3D brain model, cf. Fig.
19.8
(right).
19.4 Summary and Outlook
An appropriate constitutive model based on the TPM was presented, which is able to
capture the infusion process of therapeutic agents into the brain tissue. All existing
physical constituents are included in the modeling approach and a reasonable con-
sideration of anisotropies and heterogeneities of the white-matter tracts was carried
out, as this influences the observed irregular distribution of the infused therapeutic
agents. The investigated model is able to describe the physical effects in a qualita-
tive correct manner. If profound material parameters can be found in the future (by
