Localized measurement and mapping of tissue nonlinear elasticity

Project: Research project

Description

AbstractPalpation has been used for hundreds of years in medicine to differentiate various types of tissues and masseswithin tissue. In technical terms, palpation can be defined as deformation of tissue in response to a force,which in linear mechanics is defined as tissue elasticity. The concept of tissue elasticity i.e. elastography hasbeen the subject of intense investigations in the past two decades. However, recent studies have shown thattissue behaves nonlinearly at larger strains, whereby the nonlinear elasticity of tissue may carry importantdiagnostic information. The long-term objective of this research is the development of a novel diagnostictechnique that (i) makes use of the acoustic radiation force (ARF) for noninvasive tissue interrogation, and (ii)deploys a novel coefficient of nonlinear tissue elasticity as a biomarker that is sensitive to tissue type. Onepossible application of the method, initiated in this study, is the differentiation of breast masses; however, theproposed method may find applications in other organs. The proposed study is made possible by the recentdiscovery by our research team that the magnitude of the ARF in soft tissues depends linearly on a particularcoefficient of nonlinear tissue elasticity, hereon denoted by C ? that quantifies the gain in shear wave speeddue to increasing hydrostatic pressure. The basic idea behind the method is to act upon tissue by the ARF at apoint of interest (e.g. inside a breast mass) and to monitor the ARF-generated generated shear waves viaultrasound. In this setting, the nonlinear modulus C can be computed from the amplitude of the observed shearwaves ? a claim that is supported by our preliminary data on tissue-mimicking phantoms and animal tissues.The proposed approach to nonlinear tissue elastography is novel in that: (a) it focuses on the volumetric-shearmodulus C that has eluded previous studies, and (b) it enables, for the first time, local evaluation of nonlineartissue elasticity with a spatial resolution given by the size of the focal region (order of mm). This makes itpossible to locally measure C over the volume of the focal region using the ARF. For this reason, the proposedmethod is hereon referred to as nonlinear C-Elastography (CE). To assess the effectiveness of CE, we firstpropose to create well-characterized phantoms with (tissue-mimicking) lesions and create their C-images to becompared with the respective linear (e.g. shear modulus) elastograms. The last stage of our study would focuson the ex-vivo testing of breast masses, through which we will be able to correlate the CE results to tissuepathology and assess the overall effectiveness of CE. Successful completion of this research will spur thedevelopment of a noninvasive, diagnostic tool that may have significant impact in early differentiation ofbreast masses and potentially pathologies in other organs.
StatusFinished
Effective start/end date7/1/166/30/18

Funding

  • National Institutes of Health: $209,921.00

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elastic properties
sound waves
breast
organs
S waves
biomarkers
interrogation
pathology
medicine
hydrostatic pressure
lesions
animals
spatial resolution
shear