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Systematic quantification of differences in shear wave elastography estimates between linear-elastic and viscoelastic
Sapna R Bisht1, Abhijit Paul1, Panchami Patel2
1Department of Biological Sciences and Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat 382355, India.
The Journal of the Acoustical Society of America
|March 12, 2024
Summary
Shear wave elastography (SWE) can overestimate tissue stiffness by up to 76% when assuming linear elasticity instead of viscoelasticity. This study highlights the need for viscoelasticity estimation in SWE for accurate biomarker development.
Area of Science:
- Biomedical Engineering
- Medical Imaging
- Acoustics
Background:
- Quantitative metrics are crucial for reliable shear wave elastography (SWE) biomarkers.
- The linear-elastic material assumption has been standard in SWE for over two decades.
- Viscoelasticity estimation methods are emerging in clinical SWE systems.
Purpose of the Study:
- To systematically quantify differences in SWE estimates between linear-elastic and viscoelastic material assumptions.
- To elucidate the impact of material viscosity and shear modulus on SWE estimates using a simulation framework.
Main Methods:
- Developed an acousto-mechanical simulation framework for acoustic radiation force impulse-based SWE.
- Assessed SWE estimates using numerical viscoelastic phantoms, polyvinyl alcohol phantoms, and ex vivo liver tissue.
- Compared SWE estimates with rheometry under both linear-elastic and viscoelastic (Kelvin-Voigt) models.
Main Results:
- Linear-elastic assumption caused up to 72% error in shear modulus estimates of viscoelastic phantoms.
- No significant difference in shear modulus estimates between rheometry and SWE using the Kelvin-Voigt model.
- Linear-elastic assumption resulted in 50.1%-62.1% difference compared to rheometry in PVA phantoms and 76.1% in ex vivo liver.
Conclusions:
- Using a linear-elastic assumption for viscoelastic tissues in SWE can introduce significant errors.
- Viscoelasticity estimation methods are essential for developing robust and accurate quantitative SWE imaging biomarkers.
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