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NON-LINEAR MECHANICAL PROPERTY RECONSTRUCTION OF HOMOGENEOUS GELATINE PHANTOMS

INTERNATIONAL JOURNAL OF c 2006Institute for Scientific INFORMATION AND SYSTEMS SCIENCES Computing and Information Volume2,Number4,Pages512–521

DIGITAL IMAGE-BASED ELASTO-TOMOGRAPHY:

NON-LINEAR MECHANICAL PROPERTY RECONSTRUCTION OF HOMOGENEOUS GELATINE PHANTOMS

ASHTON PETERS,HANS UWE-BERGER,J.GEOFFREY CHASE,AND

ELIJAH E.W.VAN HOUTEN

Abstract.Experimental results in the application of a gradient descent to-

mographic elasticity reconstruction method to measured soft tissue phantom

data are presented.Surface motions at a limited number of measurement sites

were used to reconstruct a global stiffness parameter for a homogeneous gela-

tine phantom.Results corresponded well with expected values and simulated

experiments.Variation in reconstructed stiffness values was much lower than

estimated noise levels within the measured motion data.Resonance behavior in

the reconstruction model caused a portion of initial guesses to fail to converge,

although in all cases the majority of initial guesses converged to the correct

result.

Key http://www.doczj.com/doc/2f0097ecaeaad1f346933fd3.html putational mechanics,elasticity,finite element method,in-

verse problem

1.Introduction

The ability to detect abnormal lesions within the breast by manual palpation is a direct result of the underlying mechanical properties of the breast tissue involved. Cancerous tissue appears significantly stiffer than healthy breast tissue when com-pressed as a consequence of its dense cellular structure.Mechanical testing studies performed to date indicate that invasive ductal carcinoma are up to an order of magnitude stiffer than healthyfibroglandular breast tissue[1,2].

Elastographic techniques for breast imaging are based on the inherent stiffness contrast of cancerous tissue.A key advantage of elastography is that this mechan-ical stiffness contrast is far greater than the x-ray attenuation contrast measured with a screen-film mammogram,regarded as the gold standard for breast cancer screening[3].Several groups have had success in reconstructing the elastic proper-ties of the breast volume using different elastographic methods,particularly Mag-netic Resonance(MR)elastography and ultrasound elastography[4,5,6,7].Both techniques have yielded comparable results to direct mechanical measurement.

Digital Image-based Elasto-Tomography(DIET)is a novel soft tissue elastogra-phy method currently under development.The DIET system uses surface motion as input to an inverse reconstruction algorithm that calculates the internal stiffness distrib
ution of the sample being examined.The limitation to surface data makes this reconstruction problem even more ill-posed than modalities such as MR elas-tography where full volume data sets are used.However,the ability to obtain the

Digital Image-based Elasto-Tomography(DIET)is a novel soft tissue elastogra-phy method currently under development.The DIET system uses surface motion as input to an inverse reconstruction algorithm that calculates the internal stiffness distribution of the sample being examined.The limitation to surface data makes this reconstruction problem even more ill-posed than modalities such as MR elas-tography where full volume data sets are used.However,the ability to obtain the

Received by the editors January1,2006and,in revised form,March22,2006.

2000Mathematics Subject Classification.35R35,49J40,60G40.

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