Biomedical Engineering Reference
In-Depth Information
5 Results
The estimated material parameters obtained using the homogeneous and heteroge-
neous models are presented in Table
1
together with the prediction errors for the
skin, muscle and nipple locations. The total nipple displacement identified between
the prone and aligned supine MR images was 45.3 mm and provides a measure of
the magnitude of deformation seen between the two different positions. Figure
4
presents the homogenous and heterogeneous results for the skin and nipple while
Fig.
5
presents the result for the muscle. The maximum error reduced by 4.5 mm
when comparing the heterogeneous model (9.3 mm max error) against the homo-
geneous model (13.8 mm max error).
Table 1 Homogeneous and heterogeneous model parameter estimates showing mean skin,
muscle and nipple displacement errors
Parameters (kPa)
Skin RMSE (mm) Muscle RMSE (mm) Nipple displacement error (mm)
c
homog
4.2
4.0
9.5
0.07
c
breast-tissue
c
muscle
5.0
3.2
6.7
0.05
0.26
Fig. 4 Homogeneous (
left
) and heterogeneous (
right
) prone to supine FE model simulation
results, where the
green/light grey
and
red/dark grey spheres
indicate the predicted and the actual
(reference) nipple positions and the
colour/grey scale bar
indicates skin error (mm)
