Cross-plane shear wave elastography for viscoelasticity imaging.

Area of Science:

• Biomedical Imaging
• Ultrasound Technology
• Biophysics

Background:

• Conventional shear wave elastography (SWE) is limited to 2D planes, hindering comprehensive tissue analysis.
• Viscosity, a measure of shear wave dissipation, is an emerging biomarker for disease progression, but current SWE lacks sensitivity to it.
• Extending SWE beyond 2D planes is crucial for advanced viscoelasticity imaging.

Purpose of the Study:

• To develop and validate a method for extending SWE-based viscoelasticity imaging beyond the 2D measurement plane.
• To incorporate viscosity measurements as a key biomarker for disease progression.
• To enhance SWE capabilities for more comprehensive tissue characterization.

Main Methods:

• A cross-plane acquisition strategy was implemented, recording multiple measurement planes per acoustic radiation force (ARF) push.
• Full-waveform inversion (FWI) with H1 regularization was employed for stable and accurate reconstruction of elasticity (G) and viscosity (eta).
• Validation was performed using synthetic datasets with varying parameters and noise levels, employing a multiresolution sequential inversion framework.

Main Results:

• The cross-plane strategy significantly improved viscosity distribution recovery by capturing inter-plane dissipative behavior.
• H1 regularization enhanced reconstruction stability and reduced artifacts without compromising resolution.
• Viscosity reconstructions showed improved boundary fidelity and reduced ambiguity compared to single-plane methods, while elasticity maps remained consistent.

Conclusions:

• The study demonstrates the feasibility of reconstructing volumetric viscoelastic properties using cross-plane SWE.
• The developed framework paves the way for true 3D viscoelastic imaging using standard 2D ultrasound acquisitions.
• This method offers a pathway to improved disease diagnosis and monitoring through enhanced tissue characterization.