Kongkuo Lu and William E. Higgins Penn State University Department of Electrical Engineering University Park, PA 16802, USA Improved 3D Live-Wire Method with Application to 3D CT Chest Image Analysis SPIE Medical Imaging 2006: Image Processing, San Diego, CA, 14 Feb

Motivation  ROI segmentation is important, but difficult  Manual slice tracing always works --but it is time consuming  Automated segmentation avoids user intervention --but it is strongly application dependent  Semiautomatic methods allow for full user control while reducing human involvement

Prior Work  Mortensen et al. (IEEE Computers in Cardiology 1992)  Mortensen et al. (Graphical Models and Medical Imaging 1998)  Falcão et al. (SPIE Medical Imaging 1996)  Falcão et al. (Graphical Models and Medical Imaging 1998) 2D Live Wire:   Falcão et al. (Medical Image Analysis 2000)   Schenk et al. (MICCAI 2000)   Salah et al. (Workshop Bildverarbeitung in der Medizin 2005)   Hamarneh et al. (SPIE Medical Imaging 2005)   König et al. (SPIE Medical Imaging 2005) 3D Live Wire:

Cost Function Image FeatureCost Laplacian Zero-Crossing Gradient Magnitude Gradient Direction Secondary Gradient Direction Cost Function: New Cost! * Three components were derived from Mortensen 98

Gradient Direction D(p) D(r)p r |r-p| D’(r) D’(p) D(p) D(r) p r|r-p|D’(r) D’(p) Gradient Direction: New Gradient Direction: D(r) p r|r-p|D’(r) D’(p)

Gradient Direction Live Wire using old costLive wire with new cost

2D Graph-Search Algorithm 2D graph-search algorithm for the live-wire method (Modified based on Mortensen 98)

2D Live Wire Introduction * Derived from Mortensen 98

2D Live Wire Example Segment ROI using 2D Live Wire

3D Live Wire Trans. Sag. Coro. 2D live wire on Sag. slice 1 2D live wire on 2 Coro. slices Running 3D live wire in Trans. direction 2D live wire on Sag. slice 2 Generate seeds on every slice in Trans. direction

3D Live Wire Slice i Slice i+1 Slice i-1 Slice i+2 Slice i-2 Distance Distance Reference Slice 2D live wire on ref. slice Proj. result onto neighbor slices Define boundaries using 2D live wire Proj. results onto following slices

2D Results 2D ROI Segmentation result * Three ROIs used in tests

2D Live Wire Evaluation Three Factors: ( derived from Three Factors: ( derived from Falcão98, 00 ) Efficiency -- Processing time to segment an ROI Repeatability -- Accuracy --

2D Live Wire Evaluation Segmentation Reproducibilities Inter-Operator Segmentation Reproducibilities

2D Live Wire Evaluation R 21 R 22 R 23 Efficiency23.4s13s18.6s Repeatability97.86%98.57%98% Accuracy98.38%98.76%97.68% Summary: Time ratio between manual tracing and 2D live wire: R 21 R 22 R 23 2D Live Wire23.4s13s18.6s Manual Slice Tracing310s192s278s Time Ratio * Efficiency comparison based on accuracy higher than 95%

3D Results * Three 3D ROIs used in tests ROI R 33 ROI R 32 ROI R 31

3D Results 3D Segmentation Results

3D Live Wire Evaluation R 31 R 32 R 33 Efficiency34s95s8m9s Repeatability97.64%97.88%96.87% Accuracy98.08%98.12%97.16% Summary: Time ratio between 3D live wire and 2D live wire / manual slice tracing: R 21 R 22 R 23 2D LW vs. 3D LW Manual vs. 3D LW * Efficiency comparison based on accuracy higher than 90%

3D Live Wire Example

Comments on 3D Live Wire Topview Bottomview

Summary  Introduce new gradient direction cost  2D live wire works very well 2D Live Wire: 3D Live Wire:   Reliable and efficient