Does group velocity always reflect elastic modulus in shear wave elastography?

Ivan Pelivanov, Liang Gao, John Pitre, Mitchell A. Kirby, Shaozhen Song, David Li, Tueng T. Shen, Ruikang K. Wang, Matthew O'Donnell

Research output: Contribution to journalArticlepeer-review

Abstract

Dynamic elastography is an attractive method to evaluate tissue biomechanical properties. Recently, it was extended from US-and MR-based modalities to optical ones, such as optical coherence tomography for three-dimensional (3-D) imaging of propagating mechanical waves in subsurface regions of soft tissues, such as the eye. The measured group velocity is often used to convert wave speed maps into 3-D images of the elastic modulus distribution based on the assumption of bulk shear waves. However, the specific geometry of OCE measurements in bounded materials such as the cornea and skin calls into question elasticity reconstruction assuming a simple relationship between group velocity and shear modulus. We show that in layered media the bulk shear wave assumption results in highly underestimated shear modulus reconstructions and significant structural artifacts in modulus images. We urge the OCE community to be careful in using the group velocity to evaluate tissue elasticity and to focus on developing robust reconstruction methods to accurately reconstruct images of the shear elastic modulus in bounded media.

Original languageEnglish (US)
Article number076003
JournalJournal of biomedical optics
Volume24
Issue number7
DOIs
StatePublished - Jul 1 2019

Keywords

  • Dynamic elastography
  • Group velocity
  • Optical coherence elastography
  • Optical coherence tomography
  • Shear modulus
  • Tissue elasticity

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Biomedical Engineering

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