Ultrasound elastography using shear wave interference patterns: a finite element study of affecting factors

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Acoustics

Background:

• Elastography is a non-invasive imaging technique to assess tissue stiffness.
• Shear Wave Interference Patterns (SWIP) elastography offers a rate-independent approach.
• Sonoelastography maps tissue displacements using ultrasonic imaging.

Purpose of the Study:

• To simulate a finite element model (FEM) of viscoelastic soft tissue with a stiffer lesion.
• To investigate the impact of stimulation characteristics on SWIP propagation and shear speed map reconstruction.
• To propose a novel elastography probe for experimental validation.

Main Methods:

• Utilized a finite element model (FEM) to simulate SWIP in a viscoelastic phantom with a stiffer inclusion.
• Employed two external continuous harmonic vibration sources to induce SWIP.
• Mapped tissue displacements using ultrasound imaging (sonoelastography).
• Calculated elastographic average speed ratio (ASR), Dice, and Jaccard coefficients to quantify parameter effects.

Main Results:

• Simulation results demonstrate that improper parameter selection leads to divergence in ASR, Dice, and Jaccard scores from the FEM ground truth.
• Optimal vibration parameter selection yielded high Dice (≈0.9) and Jaccard (≈0.8) coefficients for the shear speed map.
• The proposed elastography probe design is suitable for experimental testing.

Conclusions:

• Careful selection of harmonic vibration parameters is crucial for accurate SWIP elastography.
• Optimized parameters enhance the diagnostic potential of sonoelastography for detecting stiffer lesions.
• The study provides a foundation for developing more effective non-invasive diagnostic tools.