ter haar romeny, fev application of gaussian curvature: automatic colon polyp detection in virtual...
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ter Haar Romeny, FEV
Application of Gaussian curvature:
Automatic colon polyp detection in virtual endoscopy
ter Haar Romeny, FEV
MIT AI Lab
The shape index is a sensitive measurefor surface shapes
ter Haar Romeny, FEV
Enhancement byGaussian curvature
PMS
CT slice with tagged residual sticking to the wall
Same slice after electronic cleansing
Philips MS
Electronic colon cleansing
ter Haar Romeny, FEV
Current visualization
Normal doseSmooth surface
Low doseBlobs appear
Normal doseRough surface
ter Haar Romeny, FEV
Proposed solutions
Bilateral filtering blobs
Gradient smoothing rough surface
ter Haar Romeny, FEV
Results: normal dose
ter Haar Romeny, FEV
Results: all dose levels
1.6 mAs6.25 mAs64 mAs
ter Haar Romeny, FEV
Enhancement and detection of micro-vasculature:Cryo-microtome images of the goat heart
• Very high resolution:• about 40×40×40 µm;• Continuous volume• Huge stacks (billions of voxels, millions of vessels)• Strange PSF in direction perpendicular to slices• Scattering• Broad range of vessel sizes and intensities.
8 cm = 2000 pixels
MSc thesis Edwin Bennink, 2007
ter Haar Romeny, FEV
The Cryomicrotome
Coronary arteries of a goat heart are filled with a fluorescent dye;Cryo: The heart is embedded in a gel and frozen (-20°C);Microtome: The machine images the sample’s surface, scrapes off a microscopic thin slice (40 μm), images the surface, and so on …
a. b.
ter Haar Romeny, FEV
Original data
ter Haar Romeny, FEV
Dark current noise
ter Haar Romeny, FEV
Noise subtracted from data
ter Haar Romeny, FEV
Frangi’svessel-likeliness
Original data(normal and log-scale)
(The images are inverted)
ter Haar Romeny, FEV
Center linedetection
Center linesmoothing
Center line3D view
ter Haar Romeny, FEV
Vesselness: Vessel enhancement
filteringBetter delineation of small vessels
Preprocessing before MIP
Preprocessing for segmentation procedure
Frangi, W. J. Niessen, K. L. Vincken, and M. A. Viergever. Multiscale vessel enhancement filtering.
In Proc. 1st MICCAI, pages 130-137, 1998.
ter Haar Romeny, FEV
VesselnessThe second order structure is exploited for local shape properties
xx xy xz
yx yy yz
zx zy zz
I I I
H I I I
I I I
ter Haar Romeny, FEV
ter Haar Romeny, FEV
Deviation of a plate-like structure:
Similarity to blob-like structure:
Frobenius norm, second-order-like structure:
ter Haar Romeny, FEV
In the definition of vesselness the three properties are combined:
1>0 2>0 : only bright structures are detected;
, and c control the sensitivity for A, B and S;
Frangi uses = 0.5, = 0.5, c = 0.25 of the max intensity.
ter Haar Romeny, FEV
Abdominal MRA
Maximum intensity projection
No 3D information
Overlapping organs
ter Haar Romeny, FEV
2D Example: DSA
ter Haar Romeny, FEV
Scale integration:
min max
max ,V V
x x
ter Haar Romeny, FEV
Closest Vessel Projection
ter Haar Romeny, FEV
Trabecular Bone Analysis
Bone appears in two forms
Cortical Bone
Trabecular Bone
Trabecular Bone
connected network of rods & plates
loading dependent architecture
ter Haar Romeny, FEV
Stress routes
Wolff’s Law
“The internal structure and external shape of a
bone develop in response to the change in function
and forces acting upon it”
Culman Meyer
“Trabecular pattern is oriented with routes of
stress”
ter Haar Romeny, FEV
Clinical Relevance
Trabecular Architecture important parameter in bone strength (clinically proven)
Applications for in vivo analysis
determine fracture risk
monitoring structure in aging
monitor degree and development of osteoporosis
(treatment available)
monitoring malgrowth near epiphyses
placing implants and evaluating receipt
ter Haar Romeny, FEV
ter Haar Romeny, FEV
Stress Routes in Ankle
ter Haar Romeny, FEV
MR Ankle, FFE, short TE (300m)
ter Haar Romeny, FEV
CT dry femur (250m)
ter Haar Romeny, FEV
Structural Information
2D 3D Orientation PatternHigh High High High High noisy no preferred orientationHigh Low High High Low tubular structure
High Low Low platelike structureLow Low Low Low Low smooth region
ter Haar Romeny, FEV
3D orientaties
ter Haar Romeny, FEV
Dominant orientations
Orientations preferentially along anatomical axis
Histogram of 3D directions: