University of North Carolina
Comparison of Human and M-rep Kidneys Comparison of Human and M-rep Kidneys Segmented from CT ImagesSegmented from CT Images
James Chen, Gregg Tracton, James Chen, Gregg Tracton, Manjari Rao, Sarang Joshi, Manjari Rao, Sarang Joshi,
Steve Pizer, Joshua Stough, and Steve Pizer, Joshua Stough, and Ed Chaney Ed Chaney
University of North Carolina University of North Carolina Chapel HillChapel Hill
MethodsMethods
Target ImagesTarget Images: 12 planning CT images from : 12 planning CT images from archives (24 kidneys)archives (24 kidneys)
Human (A and B) segmentationHuman (A and B) segmentation: Careful : Careful slice-by-slice pixel painting (voxel-based)slice-by-slice pixel painting (voxel-based)
Computer segmentationComputer segmentation: Deformable m-reps : Deformable m-reps (yields smooth surface)(yields smooth surface)
Comparison metrics reported hereComparison metrics reported here: Volume : Volume overlap and mean surface separationoverlap and mean surface separation
University of North Carolina
The median volume overlap is measured by the overlap volume The median volume overlap is measured by the overlap volume divided by the union of the two volumes being compared.divided by the union of the two volumes being compared.
Image ChallengesImage Challenges
Poor contrast (no contrast agent)Poor contrast (no contrast agent)
Crowded soft tissue environmentCrowded soft tissue environment
Image ChallengesImage Challenges
Motion artifactsMotion artifacts
Image ChallengesImage Challenges
Image variability near renal pelvis Image variability near renal pelvis
Three human segmentations of renal pelvisThree human segmentations of renal pelvis
Three Stages of M-rep Three Stages of M-rep SegmentationSegmentation
Similarity + elongationSimilarity + elongation Atom deformationAtom deformation Boundary displacementBoundary displacement
Implied surface after each scale of segmentationImplied surface after each scale of segmentation
University of North Carolina
Result after Final StageResult after Final Stage
Limitations of ComparisonLimitations of Comparison
Segmented structures represented as Segmented structures represented as collections of whole 2 mmcollections of whole 2 mm3 3 voxelsvoxels Conversion of m-rep surfaces to voxels Conversion of m-rep surfaces to voxels introduces a bias that favors humansintroduces a bias that favors humans Sensitivity of distance ~ 2 mmSensitivity of distance ~ 2 mm Best possible volume overlap is ~ 95% Best possible volume overlap is ~ 95%
Results: Volume OverlapResults: Volume Overlap
Human A to Human B: Human A to Human B: 90%-96% 90%-96% M-rep to Human A or B: M-rep to Human A or B: 85%-95% 85%-95%
University of North Carolina
Case
Human volume overlap
0.90
0.91
0.92
0.93
0.94
0.95
0.96
0.97
Human A vs B volume overlapHuman A vs B volume overlap
Kidney NumberKidney Number
University of North Carolina
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1V
olu
me
Ove
rlap
(%
)
First Atom Boundary
M-rep vs Human A volume overlapM-rep vs Human A volume overlap
CaseCase
University of North Carolina
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Case
Ave
rag
e D
ista
nce
(cm
)A
fter
Bo
un
dar
y S
tag
e
abacbc
Results: Average Surface SeparationResults: Average Surface Separation
Human A to Human B: Within one voxelHuman A to Human B: Within one voxel
M-rep to Human A or B: Within one voxelM-rep to Human A or B: Within one voxel**
**with one exceptionwith one exception
University of North Carolina
ImageImage
ImageImage
HumanHuman
HumanHuman
M-repM-rep
M-repM-rep
Outlier CaseOutlier Case
Who is right (Human or M-rep)?Who is right (Human or M-rep)?
QuickTime™ and a decompressor
are needed to see this picture.
Movie LoopMovie Loop
ConclusionsConclusions
In this study m-reps compared In this study m-reps compared with humans A and B as well as with humans A and B as well as
A compared with B. A compared with B.
University of North Carolina
Sunset at Portsmouth IslandSunset at Portsmouth Island
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