Kongkuo Lu and William E. HigginsPenn State University

Department of Electrical EngineeringUniversity 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. 2006.

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: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:3D Live Wire:

Cost Function

Image Feature Cost

Laplacian Zero-Crossing

Gradient Magnitude

Gradient Direction

Secondary Gradient Direction

Zf

Df

Gf

),(),()()(),( qpfwqpfwqfwqfwqpl DfDfDDGGzz Cost Function:Cost Function:

DffNew New Cost!Cost!

* Three components were derived from Mortensen 98

Gradient Direction

)(1

),( 21

qpfDf

D(p)D(p)

D(r)D(r)pp

rr

|r-p||r-p|

D’(r)D’(r)

D’(p)D’(p)

1D(p)D(p)

D(r)D(r)

pprr

|r-p||r-p|2D’(r)D’(r)

D’(p)D’(p)

)(3

2),( 21

qpfDGradient Direction:

1

2

New Gradient Direction:

1

D(r)D(r)

pprr

|r-p||r-p|2D’(r)D’(r)

D’(p)D’(p)

Gradient Direction

Live Wire using old cost DffLive wire with new cost

2D Graph-Search Algorithm

2D graph-search algorithm for the live-wire method2D graph-search algorithm for the live-wire method

(Modified based on Mortensen 98)(Modified based on Mortensen 98)

2D Live Wire Introduction

292422181514481019

402820141311510511

33221920138483916

30242736292414127715

34293762393319131014

4429161320

2919171929

2523252947

33303541

* Derived from Mortensen 98

2D Live Wire Example

Segment ROI using 2D Live WireSegment ROI using 2D Live Wire

3D Live Wire

Trans.Trans.Sag.Sag.

Coro.Coro.

2D live wire on Sag. slice 12D live wire on Sag. slice 12D live wire on 2 Coro. slices2D live wire on 2 Coro. slices Running 3D live wire in Trans. Running 3D live wire in Trans. directiondirection

2D live wire on Sag. slice 22D live wire on Sag. slice 2 Generate seeds on every slice in Generate seeds on every slice in Trans. directionTrans. direction

3D Live Wire

Slice iSlice i

Slice i+1Slice i+1

Slice i-1Slice i-1

Slice i+2Slice i+2

Slice i-2Slice i-2

DistanceDistance

DistanceDistance

Reference SliceReference Slice

2D live wire on ref. slice2D live wire on ref. slice Proj. result onto neighbor slicesProj. result onto neighbor slices Define boundaries using 2D live wireDefine boundaries using 2D live wire Proj. results onto following slicesProj. results onto following slices

2D Results

2D ROI2D ROI Segmentation resultSegmentation result

* Three ROIs used in tests

2D Live Wire Evaluation

lkjnmj

lkjnmjlnkmj

EOREOR

EOREOREEOOR

BB

BBRP

22

222

)()(1

jEOR

jEOREOR

GB

GBAC

nmj

nmjnmj

2

2

2

22

)()(1

Three Factors: (Three Factors: (derived from derived from Falcão98, 00)

Efficiency --Efficiency -- Processing time to segment an ROIProcessing time to segment an ROI

Repeatability --Repeatability --

Accuracy --Accuracy --

2D Live Wire Evaluation

Segmentation Reproducibilities

Inter-Operator Segmentation Reproducibilities

2D Live Wire Evaluation

R21 R22 R23

Efficiency 23.4s 13s 18.6s

Repeatability 97.86% 98.57% 98%

Accuracy 98.38% 98.76% 97.68%

Summary:Summary:

Time ratio between manual tracing and 2D live wire:Time ratio between manual tracing and 2D live wire:

R21 R22 R23

2D Live Wire 23.4s 13s 18.6s

Manual Slice Tracing 310s 192s 278s

Time Ratio 13.25 14.77 14.95

* Efficiency comparison based on accuracy higher than 95%

3D Results

* Three 3D ROIs used in tests

ROI R33ROI R32ROI R31

3D Results

32R 3D Segmentation Results31R33R

3D Live Wire Evaluation

R31 R32 R33

Efficiency 34s 95s 8m9sRepeatability 97.64% 97.88% 96.87%

Accuracy 98.08% 98.12% 97.16%

Summary:Summary:

Time ratio between 3D live wire and Time ratio between 3D live wire and 2D live wire / manual slice tracing:2D live wire / manual slice tracing:

R21 R22 R23

2D LW vs. 3D LW 7.2 8.4 9.9

Manual vs. 3D LW 28 56 41

* Efficiency comparison based on accuracy higher than 90%

3D Live Wire Example

Comments on 3D Live Wire

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Summary

Introduce new gradient direction cost 2D live wire works very well

2D Live Wire:2D Live Wire:

3D Live Wire:3D Live Wire:

Reliable and efficient