Multi-source and multi-directional shear wave generation with intersecting steered ultrasound push beams

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Ultrasound Technology

Background:

• Elasticity imaging aids in diagnosing diseases by measuring soft tissue properties.
• Shear wave-based ultrasound elastography, including Comb-Push Ultrasound Shear Elastography (CUSE), is used for non-invasive elasticity measurements.
• CUSE utilizes multiple simultaneous ultrasound beams to generate shear waves, improving signal-to-noise ratio (SNR) and frame rates.

Purpose of the Study:

• To introduce and evaluate a novel Steered Push Beam (SPB) method for shear wave generation in ultrasound elastography.
• To compare the performance of SPB with conventional CUSE in terms of accuracy and image quality.
• To determine the optimal SPB configurations for robust shear wave speed imaging.

Main Methods:

• Simulations using Field II were performed to identify optimal SPB configurations based on shear wave intensity distribution.
• The SPB method uses unfocused ultrasound beams steered at specific angles (3-7°) to induce shear waves.
• Experiments were conducted on homogeneous and inhomogeneous phantoms with spherical and cylindrical inclusions, comparing SPB with CUSE (unfocused and focused beams).

Main Results:

• SPB method generally yielded higher contrast-to-noise ratio (CNR) and lower bias in shear wave speed reconstructions compared to CUSE.
• For a 10.4 mm cylindrical inclusion, SPB achieved CNR of 23.07-48.90 and bias of 3.78-9.22%, outperforming CUSE (CNR 18.52-22.02, bias 5.50-11.12%).
• SPB demonstrated a flexible framework for generating widely distributed shear wave sources, crucial for accurate elasticity imaging.

Conclusions:

• The Steered Push Beam (SPB) method offers improved accuracy and image quality for ultrasound shear elastography.
• SPB provides a more robust approach for elasticity measurements, particularly in detecting smaller inclusions.
• This novel technique has the potential to enhance diagnostic capabilities in various medical applications.