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30 May 2001 Novel estimators for elastography
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In conventional elastography, strains are estimated by computing gradient of estimated displacement. However, gradient-based algorithms are susceptible to noise. We have developed two new strain estimators to overcome the common limitations of elastography. The first estimator is based on a frequency-domain formulation; it estimates local strain by maximizing the correlation between the spectra of pre- and post-compression echo signals by iteratively frequency- scaling the latter. We discuss a variation of this algorithm that may be computationally more efficient. The second estimator is based on the observation that an extremely stiff region will undergo virtually no strain when compressed, and will exhibit quasi-rigid body motion. As a result, an area with high similarity between the pre- and post-compression signals indicates low strain, and an area with low similarity indicates large strain. We use normalized 2D correlation function to estimate this similarity. This method offers significant advantages for detecting rigid tissues in the presence of large, irregular, non-axial motion. Both the estimators exhibited promising results in simulation and experiments.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Sheikh Kaisar Alam, Frederick L. Lizzi, Ernest Joseph Feleppa, and T. Varghese "Novel estimators for elastography", Proc. SPIE 4325, Medical Imaging 2001: Ultrasonic Imaging and Signal Processing, (30 May 2001);


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