blood vessel modeling using 2d/3d level set method
TRANSCRIPT
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Blood Vessel Modeling using2D/3D Level Set Method
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Overview
Main Idea Big Picture Problem Considered Motivation Main Approach : Level-Set Based 2D Segmentation
Discussion Strength and Weakness of the Approach Comparison with other approaches Future Direction
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Pipeline for Blood Flow Modeling
3D Image Acquisition
Geometric Modeling
Finite ElementCalculation
Quantification,Visualization
cardivascular disease research, medical device design, and surgical planning
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What is Problem?
Construct accurate patient-specific 3D geometric models (tetrahedral mesh) of blood vessels of interest
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Why is it important?
Flow calculation using finite element method requires quality mesh
Accuracy of calculation depends on that of geometric model
Geometry Quantification
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from Image to GeomtryWhy is it difficult ? Usually requires ill-defined segmentation process
Computers easily make an error Thresholding (Isocontouring) is well defined but often it is not useful in
medical applications Noisy Scanning
Accurate Construction
Patient-Specific
Operator Dependence Minimal user interaction is favorable
Robustness Always guarantee quality result ?
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Main Approach for Geometry Path (Centerline) Construction
Semi-automatic , manual
2D image Segmentation
Surface Reconstruction thru lofting
Solid Model Operation (CSG) : Union
Automatic Mesh Generation
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Level Set Method for 2D Segmentation
Implicit Geometry Description (X) = 0 ex) x,y,z) = x + y + z -1 = 0
Evolving Geometry : (X,t)=0 t + v | grad = 0 Intuitively, move a lot on low intensity gradient area and move little on
high intensity gradient area along normal direction v : speed function , k : curvature , I : intensity
Segmentation Quality Measurement Compare segmentation with phantom geometry
2 2 2
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Surface Reconstruction Lofting
Multiple Vessels - Boolean Set Operation (Union)
Automatic Mesh Generation from solid models
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3D Level Set Method
Extend 2D to 3D No centerline necessary No lofting (interpolation) : more accurate Smooth Junction Often Hard to control (geometry & topology)
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2D level set approach
Strength Intuitive : taking
advantage of tubular shape of vessels
Clean Output Controllability
Geometry Topology
Noise Removal Robust
Weakness Heavy manual work
Centerline construction A bunch of 2D segmentation
which is not automatic Stopping criteria
Inaccurate Lofting & interpolation
Non-smooth junction Possible Self-Intersection Limited to only tubular
structure segmentation
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Comparison
2D
Segmentation
3D
Segmentation
Control Good Bad
Noise Tolerance Good Bad
Robustness Good Bad
Accuracy Bad Good
User Dependence Bad Good
Smoothness Good/Bad Good/Bad
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Conclusion
Image Based Vascular Model Construction Centerline construction Level set based 2D segmentation along centerline Surface reconstruction thru lofting Solid modeling & mesh generation
Tradeoffs : 2D vs 3D segmentation