ter haar romeny, fev application of gaussian curvature: automatic colon polyp detection in virtual...

ter Haar Romeny, FEV

Application of Gaussian curvature:

Automatic colon polyp detection in virtual endoscopy


MIT AI Lab

The shape index is a sensitive measurefor surface shapes


Enhancement byGaussian curvature

PMS

CT slice with tagged residual sticking to the wall

Same slice after electronic cleansing

Philips MS

Electronic colon cleansing


Current visualization

Normal doseSmooth surface

Low doseBlobs appear

Normal doseRough surface


Proposed solutions

Bilateral filtering blobs

Gradient smoothing rough surface


Results: normal dose


Results: all dose levels

1.6 mAs6.25 mAs64 mAs


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


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.


Original data


Dark current noise


Noise subtracted from data


Frangi’svessel-likeliness

Original data(normal and log-scale)

(The images are inverted)


Center linedetection

Center linesmoothing

Center line3D view


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.


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


Deviation of a plate-like structure:

Similarity to blob-like structure:

Frobenius norm, second-order-like structure:


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.


Abdominal MRA

Maximum intensity projection

No 3D information

Overlapping organs


2D Example: DSA


Scale integration:

min max

max ,V V

x x


Closest Vessel Projection


Trabecular Bone Analysis

Bone appears in two forms

Cortical Bone

Trabecular Bone

Trabecular Bone

connected network of rods & plates

loading dependent architecture


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”


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


Stress Routes in Ankle


MR Ankle, FFE, short TE (300m)


CT dry femur (250m)


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


3D orientaties


Dominant orientations

Orientations preferentially along anatomical axis

Histogram of 3D directions:

ter haar romeny, fev application of gaussian curvature: automatic colon polyp detection in virtual...

Documents

ter haar romeny

fev original data slide

fev enhancement

fev noise

fev results

inverted slide

fzfz slide

kzz slide