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Journal of Medical Imaging • Open Access

Further characterization of changes in axial strain elastograms due to the presence of slippery tumor boundaries
Author(s): Christopher Uff; Leo Garcia; Jeremie Fromageau; Aabir Chakraborty; Neil Dorward; Jeffrey Bamber

Paper Abstract

Elastography measures tissue strain, which can be interpreted under certain simplifying assumptions to be representative of the underlying stiffness distribution. This is useful in cancer diagnosis where tumors tend to have a different stiffness to healthy tissue and has also shown potential to provide indication of the degree of bonding at tumor–tissue boundaries, which is clinically useful because of its dependence on tumor pathology. We consider the changes in axial strain for the case of a symmetrical model undergoing uniaxial compression, studied by characterizing changes in tumor contrast transfer efficiency (CTE), inclusion to background strain contrast and strain contrast generated by slip motion, as a function of Young’s modulus contrast and applied strain. We present results from a finite element simulation and an evaluation of these results using tissue-mimicking phantoms. The simulation results show that a discontinuity in displacement data at the tumor boundary, caused by the surrounding tissue slipping past the tumor, creates a halo of “pseudostrain” across the tumor boundary. Mobile tumors also appear stiffer on elastograms than adhered tumors, to the extent that tumors that have the same Young’s modulus as the background may in fact be visible as low-strain regions, or those that are softer than the background may appear to be stiffer than the background. Tumor mobility also causes characteristic strain heterogeneity within the tumor, which exhibits low strain close to the slippery boundary and increasing strain toward the center of the tumor. These results were reproduced in phantom experiments. In addition, phantom experiments demonstrated that when fluid lubrication is present at the boundary, these effects become applied strain-dependent as well as modulus-dependent, in a systematic and characteristic manner. The knowledge generated by this study is expected to aid interpretation of clinical strain elastograms by helping to avoid misinterpretation as well as provide additional diagnostic criteria stated in the paper and stimulate further research into the application of elastography to tumor mobility assessment.

Paper Details

Date Published: 5 February 2018
PDF: 17 pages
J. Med. Imag. 5(2) 021211 doi: 10.1117/1.JMI.5.2.021211
Published in: Journal of Medical Imaging Volume 5, Issue 2
Show Author Affiliations
Christopher Uff, The Institute of Cancer Research (United Kingdom)
Leo Garcia, The Institute of Cancer Research (United Kingdom)
Jeremie Fromageau, The Institute of Cancer Research (United Kingdom)
Aabir Chakraborty, Southampton General Hospital (United Kingdom)
Neil Dorward, National Hospital for Neurology & Neurosurgery (United Kingdom)
Jeffrey Bamber, The Institute of Cancer Research (United Kingdom)
The Royal Marsden NHS Foundation Trust (United Kingdom)


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