Estimating the tumor-breast Estimating the tumor-breast volume ratio from mammogramsvolume ratio from mammograms

Jorge Rodríguez*, Pedro Linares*, Eduardo Urra*, Daniella Laya*, Jorge Rodríguez*, Pedro Linares*, Eduardo Urra*, Daniella Laya*, Felipe SaldiviaFelipe Saldivia, Aldo Reigosa , Aldo Reigosa

*Multidisciplinary Center of Visualization and Scientific Computing*Multidisciplinary Center of Visualization and Scientific ComputingFaculty of Science and Technology – University of CaraboboFaculty of Science and Technology – University of Carabobo

Biotechnological and Medical Research CenterBiotechnological and Medical Research CenterFaculty of Heath SciencesFaculty of Heath Sciences

Oncology Hospital “Miguel Pérez CarreOncology Hospital “Miguel Pérez Carreño”ño”January 2007January 2007

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IntroductionIntroduction

One woman in eight either has or will One woman in eight either has or will develop breast cancer in her lifetime.develop breast cancer in her lifetime.Once a tumor has been detected we have to Once a tumor has been detected we have to decide about the surgery.decide about the surgery.Breast conservation surgery (lumpectomy, Breast conservation surgery (lumpectomy, quadrantectomy) must be applied when it is quadrantectomy) must be applied when it is possible.possible.One of the main factors to decide which type of One of the main factors to decide which type of surgery must be used (lumpectomy, surgery must be used (lumpectomy, quadrantectomy or total mastectomy) is the quadrantectomy or total mastectomy) is the tumor-breast volume ratio tumor-breast volume ratio

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IntroductionIntroduction

Mammograms are among the best early Mammograms are among the best early detection methods detection methods

A correct decision depends on the A correct decision depends on the specialist's ability to imagine the 3D specialist's ability to imagine the 3D reconstruction from the mammograms reconstruction from the mammograms

This intuitive estimation means high This intuitive estimation means high probability of wrong decisions.probability of wrong decisions.

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The ProblemThe Problem

¿It would be possible to build a tool to ¿It would be possible to build a tool to compute the tumor-breast volume ratio compute the tumor-breast volume ratio from mammograms onlyfrom mammograms only??

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OverviewOverview1. Digitalizing lateral and cranio-caudal

mammograms.2. Segmentation of the breast and tumor from

digital mammograms.3. Mapping the mammograms over 3D planes

and establishing the spatial matching. between the projections.

4. Surface reconstruction of the tumor and breast.

5. Computing the breast-tumor volume ratio.

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SegmentationSegmentation

1. Filter based strategies failed to segment the irregular and noisy tumor contour

2. A semiautomatic and interactive strategy was chosen in order to profit the specialist experience.

3. The “Intelligent Scissors” technique was implemented

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We will detect the best way between two point on the boundary.

Segmentation with Segmentation with “intelligent scissors”“intelligent scissors”

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¿How to Chose the best path?

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The image is a discrete grid of pixels, so the contour is a piecewise of curves.

Segmentation with Segmentation with “intelligent scissors”“intelligent scissors”

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The best way is the set of pieces of curves which fit better the boundary.

Segmentation with Segmentation with “intelligent scissors”“intelligent scissors”

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The well fitted to the boundary is achieved by:

1. The gradient magnitude

2. The gradient Direction

3. The second derivative zero cross (Laplacian)

Segmentation with Segmentation with “intelligent scissors”“intelligent scissors”

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Let the image be a graph G=(V, E) where V is the set of pixels and there is and edge between two pixels when these pixels belong to the same 8-neighborhood. Also, each edge has a cost defined by a function which depends on the three previous components.

Segmentation with “intelligent Segmentation with “intelligent scissors”scissors”

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The local cost function L(p,q) from a pixel p to its 8-neighbor q, is defined as:

L(p,q)=wZ·fZ(q) + wG·fG(q) + wD·fD(p,q)

Where, wZ, wG and wD are weights. The optimal cost is given by the minimum accumulated cost that results from adding the local costs in a path from the initial to the end pixel.

Segmentación usando “intelligent Segmentación usando “intelligent scissors”scissors”

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Segmentation with “intelligent Segmentation with “intelligent scissors”scissors”

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Mapping mammograms and 3D Mapping mammograms and 3D matchingmatching

Mapping mammograms over the 3D planesMapping contours over 3D planesMatching between mapped planes (interactive process)

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Surface ReconstructionSurface Reconstruction

Projecting curves over XY plane (breast base).Defining the semi-elliptical base of the breast.Swept the plane forward and repeat.

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Surface ReconstructionSurface Reconstruction

Once all the contours has been generated, a simple contour connection algorithm is applied. No branching is present, so the correspondence between adjacent contours is trivial.Tumor is overestimated using a bounding volume (box or sphere).

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Computing the volume ratioComputing the volume ratio

Breast Volume = Ai*stepAi: Ellipse i AreaStep: Step between adjacent ellipses

Tumor volume < Bounding volume

Volumetric Ratio = Tumor volume / Breast volume

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ResultsResults

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ResultsResults

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ResultsResults

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ResultsResults

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ResultsResults

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Conclusions and Future WorkConclusions and Future Work

We have designed and implemented an useful software We have designed and implemented an useful software tool to estimate he breast-tumor volume ratio from two tool to estimate he breast-tumor volume ratio from two conventional mammogramsconventional mammogramsThe surface reconstruction of the breast has an The surface reconstruction of the breast has an acceptable appearance. acceptable appearance. Clinical validation of the software must be achieved in Clinical validation of the software must be achieved in advance. advance. Mammograms digitalizing device must be integrated to Mammograms digitalizing device must be integrated to the application.the application.The lateral-oblique mammograms must be incorporated The lateral-oblique mammograms must be incorporated to the software in order to achieve more accuracy to the software in order to achieve more accuracy reconstruction of the tumor and breast.reconstruction of the tumor and breast.

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Thanks!!!