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Explore manual and automated methods for bringing image datasets into anatomical agreement. Register multiple modalities for fusion, deformation accommodation, and image-guided surgery. Optimize with objective functions and compare signals using statistical analysis methods like Mutual Information. Learn about the EM Segmentation process for tissue posterior computation. Access free tools like 3D Slicer for visualization and analysis.
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Registration Foundations • Bring multiple image data sets into anatomical agreement
The Registration Problem Tinit . . . Tk . . . Tfinal Provided by Lilla Zollei
Applications • multi-modality fusion (same patient?) • time-series processing • e.g.: MS, fMRI experiments, cardiac ultrasound • warping across patients to atlas for labeling • accommodate tissue deformations in image-guided surgery • image-guided surgery of organs other than head
Manual Registration • Not too bad with a few data sets • Re-Position one data set for visual agreement
Automated Medical Image Registration Medical image data sets Transform (move around) Compare with objective function motion parameters score initial value Optimization algorithm Provided by Lilla Zollei
Estimate Relationship Among two Signals • U: a signal • V : another signal, transformed by
Estimate Relationship Among two Signals • If p(U,V) is Gaussian • Then best f is correlation (or squared difference)
Estimate Relationship Among two Signals • If p(U,V) is UNKNOWN • Look for strongest statistical relationship among the signals I : Mutual Information
Mutual Information (MI) • H: entropy • measures information content • I : Mutual Information - a statistic that measures lack of statistical independence
MI Registration • Default Method for Multi-Modal Medical Image Registration • Viola Wells et al. circa 96 • Collignon, and Hill & Hawkes • Pluim et al. Survey, 2003: More than 160 published applications
Example MRT Rigid Registration Pre-operative SPGR MRI Intra-operative T2-weighted MRI Provided by D. Gering
Example MRT Rigid Registration After Registration Before Registration Provided by D. Gering
“Real” CT-MR registration: 3D starting position
3D Slicer Design • Cross-platform • Built on VTK • Open source platform for visualization • GE, industrial strength • C++, Tck/TK GUI • Open GL • Library interface to graphics hardware • Easily extended • Open source • Available free: www.slicer.org
EM-Segmentation E-Step Compute tissue posteriors using current intensity correction. Estimate intensity correction using residuals based on current posteriors. M-Step Provided by T Kapur
EM Segmentation… Seg Result w/o EM Seg Result With EM PD, T2 Data
EM Segmentation: MS Example PD T2 Data provided by Charles Guttmann
EM Segmentation: MS Example Seg w/o EM Seg with EM