Distributing Synthetic Focusing Over Multiple Push-Detect Events Enhances Shear Wave Elasticity Imaging Performance

Area of Science:

• Ultrasound imaging
• Biomedical engineering
• Medical physics

Background:

• Plane wave (PW) imaging in shear wave elasticity imaging (SWEI) suffers from reduced accuracy due to unfocused beams.
• Coherent compounding is limited by SWEI's frame rate needs and transducer limitations.
• Synthetic aperture imaging (SAI) offers better focus but has lower transmission power, hindering its use in SWEI.

Purpose of the Study:

• To evaluate the performance of Hadamard-encoded distributed-multielement synthetic aperture (HDMSA) and distributed plane wave compounding (DPWC) for shear wave tracking in SWEI.
• To compare the elastographic signal-to-noise ratio (SNR_e) of HDMSA and DPWC against conventional methods.

Main Methods:

• Experiments were conducted on phantoms to assess shear wave tracking using HDMSA and DPWC.
• HDMSA utilizes Hadamard encoding for multielement SAI, distributing subapertures over multiple events.
• DPWC distributes compounding angles over multiple push-detect events.

Main Results:

• HDMSA tracking improved SNR_e by 61.6%-89.5% across different phantoms.
• DPWC tracking improved SNR_e by 56.2%-93.3% for the same phantoms.
• Both HDMSA and DPWC showed significant SNR_e improvements (28.6% and 32.5%, respectively) compared to focused ultrasound tracking.

Conclusions:

• HDMSA and DPWC offer substantial improvements in elastographic signal-to-noise ratio for shear wave tracking.
• HDMSA provides repeatable elastograms with superior performance for stationary organs in clinical settings.
• These advanced imaging techniques enhance the accuracy and precision of shear wave elasticity imaging.