Image registration Used mutual information-based registration from ITK Ben SchoepkeREU Week 36/8/07 Fixed imageMoving image Pre-registrationPost-registration
Segmentation Edema is arbitrarily shaped Ben SchoepkeREU Week 36/8/07
Mean shift segmentation Need non-parametric segmentation: mean shift! Ben SchoepkeREU Week 36/8/07 Comaniciu, D., Meer, P.: Mean shift: A robust approach toward feature space analysis. IEEE Trans. Pattern Anal. Mach. Intell. 24(5) (2002) 603–619
Experimentation Register images to T1 > Segment with mean shift > Compare Ben SchoepkeREU Week 36/8/07 T1T1e FLAIRT2 Ground truth edema estimate (un-segmented FLAIR image)
Experimentation results Observed that edema is visible in FLAIR and T2, not visible in T1 and T1E Run each segmented image through high pass filter Edema segmented image = (FLAIR && T2) && !(T1 && T1E) Problem: very sensitive to threshold selection Ben SchoepkeREU Week 36/8/07 Ground truth edema estimateResult
Next week Use brain atlas to remove false positives Probability of observing edema in CSF regions is ~0 Perform region-based analysis rather than pixel-by-pixel Continue developing algorithm Which modalities to use? Test different slices Merge with tumor segmentation code 3D segmentation Ben SchoepkeREU Week 36/8/07 Probabilistic brain atlas. Non-CSF is blue. Source: Leach et al.