3D finite-element study for multi-frequency harmonic shear wave elastography: shear wave speed contrast assessment...

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Soft Tissue Mechanics

Background:

• Soft tissue viscoelasticity is a critical biomarker for disease diagnosis.
• Accurate characterization of tissue properties is essential for medical applications.
• Shear wave elastography (SWE) techniques are vital for non-invasively assessing tissue stiffness.

Purpose of the Study:

• To investigate the effectiveness of the Harmonic Shear Wave Elastography (HSWE) framework for characterizing soft tissue viscoelasticity.
• To compare HSWE performance against the widely used Pulsed Shear Wave Elastography (PSWE) method.
• To analyze frequency-dependent phase velocity maps using a 3D Finite-Element simulation framework.

Main Methods:

• Developed and verified a 3D Finite-Element (FE) framework to model tissue displacement under multi-frequency HSWE.
• Compared HSWE results with simulation and phantom experiments against PSWE.
• Analyzed group and frequency-dependent phase velocities in the 300-800 Hz range.
• Conducted parametric studies on inclusion size, stiffness, and viscosity.

Main Results:

• HSWE provided accurate measurements of group and phase velocities, comparable to PSWE.
• Median differences between HSWE and PSWE were 5.21% (group velocity, simulation), 9.14% (phase velocity, simulation), 13.98% (group velocity, phantom), and 22.32% (phase velocity, phantom).
• HSWE effectively characterized inclusion location, size, stiffness, and viscoelastic properties, outperforming PSWE for smaller inclusions at lower frequencies.

Conclusions:

• The HSWE framework is a validated and effective tool for characterizing soft tissue viscoelasticity.
• HSWE demonstrates notable improvements over PSWE, particularly in challenging scenarios like small inclusions.
• Future work will focus on clinical optimization and developing inverse models for enhanced diagnostic capabilities.