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Viscoelastic characterization of dispersive media by inversion of a general wave propagation model in optical coherence elastography
Author(s): Fernando Zvietcovich; Jannick P. Rolland; Emma Grygotis; Sarah Wayson; Maria Helguera; Diane Dalecki; Kevin J. Parker
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Paper Abstract

Determining the mechanical properties of tissue such as elasticity and viscosity is fundamental for better understanding and assessment of pathological and physiological processes. Dynamic optical coherence elastography uses shear/surface wave propagation to estimate frequency-dependent wave speed and Young’s modulus. However, for dispersive tissues, the displacement pulse is highly damped and distorted during propagation, diminishing the effectiveness of peak tracking approaches. The majority of methods used to determine mechanical properties assume a rheological model of tissue for the calculation of viscoelastic parameters. Further, plane wave propagation is sometimes assumed which contributes to estimation errors. To overcome these limitations, we invert a general wave propagation model which incorporates (1) the initial force shape of the excitation pulse in the space-time field, (2) wave speed dispersion, (3) wave attenuation caused by the material properties of the sample, (4) wave spreading caused by the outward cylindrical propagation of the wavefronts, and (5) the rheological-independent estimation of the dispersive medium. Experiments were conducted in elastic and viscous tissue-mimicking phantoms by producing a Gaussian push using acoustic radiation force excitation, and measuring the wave propagation using a swept-source frequency domain optical coherence tomography system. Results confirm the effectiveness of the inversion method in estimating viscoelasticity in both the viscous and elastic phantoms when compared to mechanical measurements. Finally, the viscoelastic characterization of collagen hydrogels was conducted. Preliminary results indicate a relationship between collagen concentration and viscoelastic parameters which is important for tissue engineering applications.

Paper Details

Date Published: 19 February 2018
PDF: 11 pages
Proc. SPIE 10496, Optical Elastography and Tissue Biomechanics V, 104960P (19 February 2018); doi: 10.1117/12.2287553
Show Author Affiliations
Fernando Zvietcovich, Univ. of Rochester (United States)
Jannick P. Rolland, The Institute of Optics, Univ. of Rochester (United States)
Emma Grygotis, Univ. of Rochester (United States)
Sarah Wayson, Univ. of Rochester (United States)
Maria Helguera, Instituto Tecnológico José Mario Molina Pasquel y Henríquez (Mexico)
Diane Dalecki, Univ. of Rochester (United States)
Kevin J. Parker, Univ. of Rochester (United States)

Published in SPIE Proceedings Vol. 10496:
Optical Elastography and Tissue Biomechanics V
Kirill V. Larin; David D. Sampson, Editor(s)

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