Figure 1.
The analysis pipeline of the proposed classification scheme.
MAPER: multi-atlas propagation with enhanced registration; RBF: radial basis function; SVM: support vector machine.
Table 1.
Demographic features of the group of patients with temporal lobe epilepsy (TLE), controls and atlas images. Median (range) of Age and Age at onset is reported.
Figure 2.
Example segmentation result using MAPER.
Coronal section through the T1-weighted 3D MR image of a subject with left hippocampal sclerosis. The left of the subject is shown on the right of the image. Note the clear difference between the atrophic left and normal sized right hippocampus. Other volumetric differences relevant for automatic classification are invisible on visual inspection.
Figure 3.
The flowchart of the experiments on assessing the potential bias resulting from the difference in field strength between atlas images and segmentation targets.
A1, A2 and A3: groups of ten subjects from the 30 atlas datasets scanned at 1.5T. group C: ten randomly selected 3T images from the control set. Middle column top row: A1 datasets were used to anatomically segment A2 images with MAPER, resulting in automatically labeled images (A2secondary). These secondary atlas datasets were then used to segment the A3 images with MAPER. Middle column bottom row: A1 datasets used to segment group C with MAPER. The resulting ten secondarily labeled group C datasets were then used to anatomically segment the A3 images with MAPER. Last column: three sets of anatomical segmentations for A3 images: two automatically generated either via 1.5T or 3T secondary atlases, and one manual gold standard segmentation.
Figure 4.
Hippocampal volumes in patients and controls.
Horizontal lines show the medians, boxes indicate interquartile ranges, whiskers show the minimal and maximal values inside the main data, and lozenges show individual values. Blue, right hippocampi; red, left hippocampi. TLE-HA, TLE with hippocampal atrophy; TLE-N; TLE with normal MRI on visual inspection. Suffixes _L and _R denote left and right sided seizure focus, respectively.
Table 2.
Top structures ranked by ability to distinguish TLE-HA patients from controls.
Table 3.
Top structures ranked by ability to distinguish TLE-N patients from controls.
Table 4.
Sensitivity (Sens), specificity (Spec), accuracy rate (Rate) (all as percentages) and number of selected structures (D) for different experiments. Key results are shown in bold typeface.
Figure 5.
Model response curves for Experiment 1 and 4 for two classification schemes.
The classifier accuracy was presented using 83 ranked structures, for each classification experiment (baseline case).
Table 5.
T-statistic and P-value results of the permutation test based on different approaches, Volumetric study and Spectral clustering.