Segmentation of the left atrial appendage from 3D images
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Segmentation of the left atrial appendage from 3D images Pol Grasland-Mongrain 20/04/2009 – 28/08/2009
description
Segmentation of the left atrial appendage from 3D images. Pol Grasland-Mongrain 20/04/2009 – 28/08/2009. Views of the Left Atrial Appendage. Views of the Left Atrial Appendage. Variable shapes 1 to 19 cm 3 Function ? Has to be ablated sometimes. Motivation. Current implementation: - PowerPoint PPT Presentation
Transcript of Segmentation of the left atrial appendage from 3D images
Segmentation of the left atrial appendage from 3D images
Pol Grasland-Mongrain20/04/2009 – 28/08/2009
Views of the Left Atrial Appendage
Views of the Left Atrial Appendage
• Variable shapes• 1 to 19 cm3
• Function ?• Has to be ablated sometimes
Motivation
Current implementation:• LAA is represented as a short trunk in the model• Current framework not flexible enoughto grow into highly variable shape
Motivation
Motivation of my master thesis:• Addition of an Automatic SegmentationAlgorithm of the Left Atrial Appendagein the Philips Framework
Plan
I. Current Method at PhilipsII. Actual WorkIII. Results and Future Work
Philips Aachen method
New Image Segmentation Chain Segmented Image
1. HeartDetection
2. Parametric Adaptation(Similarity)
4. Deformable Adaptation
3. Parametric Adaptation
(Piecewise Affine)
Philips Aachen method
New Image Segmentation Chain Segmented Image
1. HeartDetection
2. Parametric Adaptation(Similarity)
4. Deformable Adaptation
3. Parametric Adaptation
(Piecewise Affine)
vadap = T[v]E = Eext[T]
Parametric Adaptation,Deformable Models
• Use External Energy :
Philips Aachen method
New Image Segmentation Chain Segmented Image
1. HeartDetection
2. Parametric Adaptation(Similarity)
4. Deformable Adaptation
3. Parametric Adaptation
(Piecewise Affine)
Free motion for vadap
E = Eext[v]+ α Eint[v]vadap = T[v]E = Eext[T]
Deformable Models
• Internal Energy
Plan
I. Current Method at PhilipsII. Actual Work
1. Segment manually 17 patients LAA2. Modify Philips models
1. Interface Left Atrium - Left Atrium Appendage2. Mesh which inflate
3. Code an automatic mesh-inflation algorithm1. External Energy2. Threshold between LAA – Background3. Internal Energy
III. Results and Future Work
Plan
I. Current Method at PhilipsII. Actual Work
1. Segment manually 17 patients LAA2. Modify Philips models
1. Interface Left Atrium - Left Atrium Appendage2. Mesh which inflate
3. Code an automatic mesh-inflation algorithm1. External Energy2. Threshold between LAA – Background3. Internal Energy
III. Results and Future Work
Plan
I. Current Method at PhilipsII. Actual Work
1. Segment manually 17 patients LAA2. Modify Philips model
1. Interface Left Atrium - Left Atrium Appendage2. Mesh which inflate
3. Code an automatic mesh-inflation algorithm1. External Energy2. Threshold between LAA – Background3. Internal Energy
III. Results and Future Work
Model Modification
Plan
I. Current Method at PhilipsII. Actual Work
1. Segment manually 17 patients LAA2. Modify Philips model
1. Interface Left Atrium - Left Atrium Appendage2. Mesh which inflate
3. Code an automatic mesh-inflation algorithm1. External Energy2. Threshold between LAA – Background3. Internal Energy
III. Results and Future Work
External and Internal Energies
Edge-based
Region-based
MeshReference
TriangleRegularization
Curvature N-GonRegularization
External Energy Internal Energy
External Energy :Edge-Based
• No specific features
External Energy :Region-Based
•Gray Value Above or Under ?
External Energy :Region-Growing
•Gray Value Still Above (Under) ?•Already Annotated ?
External Energy :Region-Growing
Gray Value Still Above (Under) ?Already Annotated ?•Gray Value Still Above (Under) ?•Already Annotated ?
External Energy :Region-Growing
Gray Value Still Above (Under) ?Already Annotated ?•Gray Value Still Above (Under) ?•Already Annotated ?
Threshold LAA-Myocardium
Threshold LAA-Myocardium
Threshold LAA-Myocardium
oMinimization of classification erroro Stop when Area1 = Area2
Internal Energy :Mesh Reference
• Updated Mesh
Internal Energy : Triangle Regularization
• Approximate each triangle by a rotated and scaled equilateral triangle
Internal Energy :Curvature
• Remove the peaks
Internal Energy :Curvature
• Remove the peaks
Internal Energy :N-Gon Regularization
• Approximate each “N-Gon” by a rotated and scaled regular N-Gon
External and Internal Energies
Edge-based
Region-based
MeshReference
TriangleRegularization
Curvature N-GonRegularization
External Energy Internal Energy
Plan
I. Current Method at PhilipsII. Actual WorkIII. Results and Future Work
Results
Results
• Main problem : loops -> repair
Results
Specificity = True Pos. /(True Pos. + False Neg.)
Quality = True Pos. /(True Pos. + False Pos.)
Results
0
20
40
60
80
100
Left Atrial Appendage Inflation ResultsSpecificity = True Pos. / (True Pos. + False Neg.) Quality = True Pos. / (True Pos. + False Pos.)
Sum up: • almost all segmented voxels really belong to LAA• but the mesh doesn’t inflate enough
Results
(1) (10)
(5)(7)
Majors Fails
(11) (14)
Possible future works
• Improve the loop repair :– Freeze vertices– Better correction
• Find a new internal energy ?
Thank you for your attention !
Any Questions ?
