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Variance and Covariance of Accumulated Displacement Estimates

Variance and Covariance of Accumulated Displacement Estimates Tracking large deformations in tissue using ultrasound can enable the reconstruction of nonlinear elastic parameters, but poses a challenge to displacement estimation algorithms. Such large deformations have to be broken up into steps, each of which contributes an estimation error to the final accumulated displacement map. The work reported here measured the error variance for single-step and accumulated displacement estimates using one-dimensional numerical simulations of ultrasound echo signals, subjected to tissue strain and electronic noise. The covariance between accumulation steps was also computed. These simulations show that errors due to electronic noise are negatively correlated between steps, and therefore accumulate slowly, whereas errors due to tissue deformation are positively correlated and accumulate quickly. For reasonably low electronic noise levels, the error variance in the accumulated displacement estimates is remarkably constant as a function of step size, but increases with the length of the tracking kernel. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Ultrasonic Imaging SAGE

Variance and Covariance of Accumulated Displacement Estimates

Bayer, Matthew; Hall, Timothy J.
Ultrasonic Imaging , Volume 35 (2): 19 – Apr 1, 2013
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References (26)

Publisher
SAGE
Copyright
© The Author(s) 2013
ISSN
0161-7346
eISSN
1096-0910
DOI
10.1177/0161734613479246
pmid
23493610
Publisher site
See Article on Publisher Site

Abstract

Tracking large deformations in tissue using ultrasound can enable the reconstruction of nonlinear elastic parameters, but poses a challenge to displacement estimation algorithms. Such large deformations have to be broken up into steps, each of which contributes an estimation error to the final accumulated displacement map. The work reported here measured the error variance for single-step and accumulated displacement estimates using one-dimensional numerical simulations of ultrasound echo signals, subjected to tissue strain and electronic noise. The covariance between accumulation steps was also computed. These simulations show that errors due to electronic noise are negatively correlated between steps, and therefore accumulate slowly, whereas errors due to tissue deformation are positively correlated and accumulate quickly. For reasonably low electronic noise levels, the error variance in the accumulated displacement estimates is remarkably constant as a function of step size, but increases with the length of the tracking kernel.

Journal

Ultrasonic Imaging – SAGE

Published: Apr 1, 2013

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