Biomedical Engineering Reference
In-Depth Information
V
G
= [
F G H
]
T
[
R
]
V
S
,
[15]
where
R
is a rotation matrix that transforms a vector from scanner coordinates
(
V
S
) into the FEM model coordinates
V
G
and
F
,
G
, and
H
are orthogonal geomet-
ric unit vectors computed from the ventricular geometry as described by Le
Grice et al. (67). Once the fiber vectors are represented in geometric coordinates,
DTMRI inclination and imbrication angles (B and G) are fit using a bilinear
interpolation in the local F
1
and F
2
coordinates, and a cubic Hermite interpolation
in the F
3
coordinate. A graphical user interface for fitting FEMs to both the ven-
tricular surfaces and fiber field data has been implemented using the MatLab
programming language. Figure 7 shows FEM fits to the epi- and endocardial
surfaces of a reconstructed normal canine heart obtained using this software tool.
FEM fits to the fiber orientation data are shown on these surfaces as short line
segments. We have also developed relational database and data analysis soft-
ware, named
HeartScan
, to facilitate analysis of cardiac structural and electrical
data sets obtained from populations of hearts. HeartScan enables users
Figure 7
. Finite-element model of canine ventricular anatomy showing the epicardial (red), LV
endocardial (green), and RV endocardial surfaces. Fiber orientation on each surface is shown
by short line segments.
