Analysis of correlation coefficient filtering in elasticity imaging

Sheng Wen Huang, Jonathan M. Rubin, Hua Xie, Russell S Witte, Congxian Jia, Ragnar Olafsson, Matthew O'Donnell

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

Correlation-based speckle tracking methods are commonly used in elasticity imaging to estimate displacements. In the presence of local strain, a larger window size results in larger displacement error. To reduce tracking error, we proposed a short correlation window followed by a correlation coefficient niter. Although simulation and experimental results demonstrated the efficacy of the method, it was not clear why correlation coefficient Altering reduces tracking error since tracking error increases if normalization before filtering is not applied. In this paper, we analyzed tracking errors by estimating phase variances of the cross-correlation function and the correlation coefficient at the true time lag based on statistical properties of these functions' real and imaginary parts. The role of normalization is clarified by identifying the effect of the cross-correlation function's amplitude fluctuation on the function's imaginary part. Furthermore, we present analytic forms for predicting axial displacement error as a function of strain, system parameters (signal-to-noise ratio, center frequency, and signal and noise bandwidths), and tracking parameters (window and Alter sizes) for cases with and without normalization before Altering. Simulation results correspond to theory well for both noise-free cases and general cases with an empirical correction term included for strains up to 4%.

Original languageEnglish (US)
Article number4686874
Pages (from-to)2426-2441
Number of pages16
JournalIEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Volume55
Issue number11
DOIs
Publication statusPublished - Nov 2008

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ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Acoustics and Ultrasonics
  • Instrumentation

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