Docteur de l'université Automatic Segmentation and Shape Analysis ...

124 Chapter 5 Quantitative shape analysis of hippocampus in AD
Accuracy
Accuracy
0.75 0.77 0.79
●
● ●
● ●●
● ●
● ●●●
●
●
●
● ●
●
●
●
● ●
●●
●
● ● ●● ●●
●
●
●
● ● ●
●
●●
●●
● ● ●
●
●
●
●
●
●●●● ●
●
●●
●
● ●●●●
● ●●
●
●
●
1e−04 1e−03 1e−02 1e−01 1e+00
Threshold α
(a) OOB accuracy, LR, MR
0.68 0.72 0.76 0.80
●
●
● ●
● ● ●●
● ●
● ●
●
●
● ●
● ●
● ● ● ●
●
●●
● ● ● ●●●
● ●
● ●
●●
● ● ●●
●
●
●
●●
● ● ● ● ●
●●
●
●
● ● ●
●●
● ●
●
●
●
●
1e−04 1e−03 1e−02 1e−01 1e+00
Threshold α
(c) OOB accuracy, LS, MR
Accuracy
Accuracy
0.71 0.73 0.75 0.77
●
●
● ●●●
● ●
● ●
● ● ● ●
●●●
● ● ●
●
●
● ●
●
●
● ●
●
●
● ●
●
●
●●
●●
●
● ●
● ● ●
●
●
● ●
● ● ●
●
● ●
●
● ●
● ●
1e−04 1e−03 1e−02 1e−01 1e+00
Threshold α
●
●●
(b) OOB accuracy, LR, MS
0.70 0.75 0.80
●●
●
●
●
●
● ●● ●
● ●
●
●
● ●
●
●
● ●
● ●
●
●
●
●
● ●
●
●
●
● ● ● ●
● ●
●
●
●
● ●
●
●●●
●
●
●
●● ●
●
●
●
●●
●
● ●
● ●
●
● ●
●
●
1e−04 1e−03 1e−02 1e−01 1e+00
Threshold α
(d) OOB accuracy, LS, MS
Figure 5.5: The training accuracy of the disease classification using bagged
support vector machines (SVMs) with varying thresholds in the landmark selection.
The out-of-bag (OOB) estimates is used for the measure of the training
error. Black circles: shape features from the Statistical Shape Model (SSM)
only; red circles: shape features with additional volume features.
5.5.4 Correlation of hippocampal SSM descriptors with memory scores
The results of the correlation between the memory scores and the hippocampal
shape variation over all landmarks, landmarks selected with threshold α = 0.1,
and threshold α = 0.01 are shown in Figure 5.11. The component in each SSM
with the strongest correlation with the memory scores are plotted. The principal
variations in the model on the selected subregions are shown to be better correlated
with memory scores. Stronger correlations were found by the models built on LS
identified regions. The highest correlation between the memory score and the hip-
pocampal shape was captured by similarity aligned SSM (MS) on the hippocampal
subregions masked using LS with threshold at α = 0.01, in which the first princi-
pal component was the most correlated component with AVLT, Logical Memory
scores (both immediate and delayed recall), and memory subscores of ADAS for