Level-Set Evolution with Region Competition: Automatic 3-D Segmentation of Brain Tumors 1 Sean Ho, 2 Elizabeth Bullitt, and 1;3 Guido Gerig 1 Department of Computer Science, 2 Department of Surgery, 3 Department of Psychiatry University of North Carolina, Chapel Hill, NC, USA Supported by NIH-NCI R01 CA Partially supported by NIH-NCI P01 CA47982.
Tumor segmentation Focusing on meningiomas and glioblastomas Focusing on meningiomas and glioblastomas Glioblastomas have a ring enhancement that makes segmentation tough Glioblastomas have a ring enhancement that makes segmentation tough
Overview of the procedure 1. Multiparameter MR image data 2. Fuzzy voxel-based segmentation 3. Level-set snake driven by: 1. Region competition 2. Smoothness constraints Can use alone for enhancing tumors Can use alone for enhancing tumors Or as part of the tumor/tissue/vasculature segmentation Or as part of the tumor/tissue/vasculature segmentation
Multiparameter MR images T1GAD-T1 registered difference image T1GAD-T1 registered difference image T2 available but not used in this work T2 available but not used in this work = -
Probability map of enhancing tissue T1GAD-T1 registered difference image T1GAD-T1 registered difference image Mixture-model histogram fit: Mixture-model histogram fit: Gaussian for the background Gaussian for the background Gamma function for the contrast agent uptake Gamma function for the contrast agent uptake
Region competition snake Image force: modulate propagation by signed inside/outside force Image force: modulate propagation by signed inside/outside force Smoothness constraint: Smoothness constraint: Mean curvature flow Mean curvature flow Gaussian smoothing of the implicit function Gaussian smoothing of the implicit function
Enhancement => image force
Live demo
Results Very challenging segmentation problem, even for expert manual segmentation: Very challenging segmentation problem, even for expert manual segmentation: Complex tumor geometry Complex tumor geometry Complex greylevel appearance Complex greylevel appearance Nearby enhancing structures (e.g. vessels, bone) Nearby enhancing structures (e.g. vessels, bone) Some examples: Some examples:
Validation Compared against expert human rater Compared against expert human rater Validation with 2 nd human rater in progress Validation with 2 nd human rater in progress More tumor datasets on the way More tumor datasets on the way Dataset Volume Overlap Hausdorff (mm) In (mm) Out (mm) Average (mm) Tumor % Tumor % Tumor %
Integrating in the “ Big Picture ” Modify atlas with subject specific pathology Modify atlas with subject specific pathology Probability map of enhancing tissue Probability map of enhancing tissue Region-competition snake Region-competition snake Smoothness constraints Smoothness constraints EM tissue classification (previous talk): EM tissue classification (previous talk): Using spatial prior Using spatial prior Additional tumor and edema classes Additional tumor and edema classes Bias field inhomogeneity compensation Bias field inhomogeneity compensation Result: Combined tumor and tissue segmentation (gm, wm, csf, edema) Result: Combined tumor and tissue segmentation (gm, wm, csf, edema)
The “ Big Picture ”, cont. Tumor segmentation registered with segmentation of vasculature: Tumor segmentation registered with segmentation of vasculature: We also have MRA images We also have MRA images Vessel extraction software Vessel extraction software
Free software downloads midag.cs.unc.edu midag.cs.unc.edu SNAP (prototype): SNAP (prototype): 3D level-set evolution 3D level-set evolution Preprocessing pipeline and manual editing Preprocessing pipeline and manual editing VALMET (prototype) VALMET (prototype)