Ter Haar Romeny, FEV MIT AI Lab Automatic Polyp Detection.
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Transcript of Ter Haar Romeny, FEV MIT AI Lab Automatic Polyp Detection.
![Page 1: Ter Haar Romeny, FEV MIT AI Lab Automatic Polyp Detection.](https://reader035.fdocuments.net/reader035/viewer/2022062404/551a7306550346b52d8b502e/html5/thumbnails/1.jpg)
ter Haar Romeny, FEV
MIT AI Lab
AutomaticPolypDetection
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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
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ter Haar Romeny, FEV
Current visualization
Normal doseSmooth surface
Low doseBlobs appear
Normal doseRough surface
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ter Haar Romeny, FEV
Proposed solutions
Bilateral filtering blobs
Gradient smoothing rough surface
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ter Haar Romeny, FEV
Results: normal dose
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ter Haar Romeny, FEV
Results: all dose levels
1.6 mAs 6.25 mAs 64 mAs
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ter Haar Romeny, FEV
Extract vasculature with ‘vesselness’
From T1w MRI with contrast
Frangi’s vesselness measure [Frangi et al., 1998]
Enhance tubular structures while reducing other morphologies
E. Brunenberg, MSc project
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ter Haar Romeny, FEV
Vesselness measure
Based on eigenvalue analysis
of Hessian:
two low eigenvalues
one high eigenvalue
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ter Haar Romeny, FEV
Vesselness - 1
Eigenvalue analysis of Hessian:
extract directions of principal curvature
Hessian:
where
and
xx xy xz
yx yy yz
zx zy zz
I I I
H I I I
I I I
G
I2
2 ,I
xx x
G e
2
223
2
1,
2
x
x
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ter Haar Romeny, FEV
Vesselness - 2Eigenvalues ordered as |λ1| ≤ |λ2| ≤ |λ3|
Bright vessel region: λ1 small, ideally zero; λ2 and λ3 large
but negative.
Ratio for blobness:
Ratio for plate-like:
Image structure:
BR1
2 3
,1 forblob-like
AR2
3
,0 for line-like
S 2 2 21 2 3 ,1 formuch contrast
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ter Haar Romeny, FEV
Vesselness - 3
Total vesselness function:
Parameters:
α = β = 0.5
c = 0.5 * maximum Hessian norm
Multiscale approach:
22 2
22 2
2 3
22 2
0 if 0 or 0
,1 1 otherwise
BARR S
cV
e e e
x
min max
max ,V V
x x
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ter Haar Romeny, FEV
Vessel enhancement filtering
Better delineation of small vessels
Preprocessing before MIP
Preprocessing for segmentation procedure
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ter Haar Romeny, FEV
Abdominal MRA
Maximum intensity projection
No 3D information
Overlapping organs
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ter Haar Romeny, FEV
2D Example: DSA
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ter Haar Romeny, FEV
Scale integration
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ter Haar Romeny, FEV
Closest Vessel Projection
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ter Haar Romeny, FEV
Trabecular Bone
Bone appears in two forms
Cortical Bone
Trabecular Bone
Trabecular Bone
connected network of rods & plates
loading dependent architecture Wiro Niessen, PhD
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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”
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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
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ter Haar Romeny, FEV
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ter Haar Romeny, FEV
Stress Routes in Ankle
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ter Haar Romeny, FEV
MR Ankle, FFE, short TE (300m)
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ter Haar Romeny, FEV
CT dry femur (250m)
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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
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ter Haar Romeny, FEV
3D orientaties
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ter Haar Romeny, FEV
Dominant orientations
Orientations preferentially along anatomical axis
Histogram of 3D directions: