Modeling of the acoustic radiation force in elastography

Area of Science:

• Medical Imaging
• Biophysics
• Acoustics

Background:

• Elastography assesses in vivo tissue stiffness non-invasively.
• Shear wave elastography uses acoustic radiation force (ARF) from ultrasound to generate shear waves.
• Accurate ARF modeling is essential for reliable elastography.

Purpose of the Study:

• Compare three acoustic radiation force (ARF) formulations for shear wave elastography.
• Analyze discrepancies between full, quasi-plane wave, and attenuated plane wave approximations.
• Evaluate the impact of these formulations on shear displacement calculations.

Main Methods:

• Derived analytical expressions for ARF with spherical and quasi-Gaussian beams.
• Incorporated three ARF formulations into the k-Wave simulation package.
• Computed ARF and shear displacements using conventional ultrasound probes.

Main Results:

• Significant discrepancies exist between ARF formulations, especially for divergent/focused beams.
• Second-order and quasi-plane wave approximations yield nearly identical shear displacements.
• The attenuated plane wave approximation showed significant differences in displacement calculations.

Conclusions:

• The second-order or quasi-plane wave ARF approximations are preferred for accurate shear wave elastography.
• These approximations properly account for ultrasound field structure in simulations.
• Choosing the correct ARF formulation is vital for precise tissue stiffness measurements.