Shear-Wave Pulse-Compression Elastography using a Modulated Acoustic Radiation Force Excitation

Ultrasound shear wave elastography is a technique that induces shear waves in soft tissues through dynamic stress, thereby enabling the assessment of their elasticity by measuring wave velocity. However, limitations in ultrasound imaging, including shadowing, endogenous motion, reverberation, and depth-dependent attenuation, often result in low signal-to-noise ratio (SNR) signals, which present significant challenges for capturing shear waves. To address this issue, we propose a novel shear wave generation method based on acoustic radiation force (ARF) pulses modulated with binary maximum-length sequences (MLS). The method employs a binary-modulated ARF to induce tissue motion, which is then deconvolved with the pulse-coded excitation. The MLS deconvolution results in a broadband impulse response, thereby enabling the recovery of the compressed shear-wave pulse shape over the excitation frequency band and, moreover, enhancing the displacement amplitude and SNR. The initial experimental outcomes indicate that the use of extended coded-excitation ARF pulses results in an SNR gain exceeding 10 dB, attributable to pulse compression. By enhancing the quality of displacement data and reducing noise, the method fortifies the reliability of algorithms utilized to estimate shear wave speed, minimizing the potential for biased outcomes.