Forward and inverse viscoelastic wave scattering by irregular inclusions for shear wave elastography

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Acoustic Elastography

Background:

• Current shear wave elastography methods use simplifying assumptions, leading to artifacts in tissues with high stiffness contrasts.
• Existing techniques do not provide viscosity maps, limiting their ability to characterize complex tissue mechanics.

Purpose of the Study:

• To develop and validate an inverse problem approach for estimating viscoelastic properties of inclusions and surrounding media.
• To accurately map the geometry and mechanical properties of inclusions in soft tissues using shear wave fields.

Main Methods:

• Developed a semi-analytical model using Bessel functions and Fourier series for elastic wave scattering by irregular inclusions.
• Validated the model against finite element modeling.
• Experimentally induced shear waves using acoustic radiation force and imaged displacement fields with plane wave imaging.
• Employed a nonlinear least-squares algorithm to fit the model to experimental data and estimate parameters.

Main Results:

• The developed method accurately estimated shear storage and loss moduli, showing good agreement with reference measurements.
• Inclusion shape estimation was also accurate.
• The approach demonstrated reliable characterization of viscoelastic properties and geometry for inclusions in homogeneous backgrounds.

Conclusions:

• This inverse problem approach accurately estimates geometry and viscoelastic properties for single inclusions in homogeneous backgrounds within radiation force elastography.
• The method overcomes limitations of traditional inversion techniques, offering improved accuracy for tissues with strong stiffness contrasts.
• Provides a valuable tool for quantitative assessment of soft tissue mechanical properties in medical imaging.