SAW Motion Artifact Correction Using Bone Echoes in Wearable Ultrasound Shear-Wave Elastometry

Monitoring muscle mechanical properties is important for assessing neuromuscular function in health, rehabilitation, and human-machine interfacing. Wearable ultrasound shear-wave elastometry (wUS-SWEM) enables continuous monitoring of muscle mechanical properties during contraction or movements by measuring shear-wave velocity (SWV). However, the skin-mounted actuator not only generates shear waves (SWs) in the target muscle but also excites surface acoustic waves (SAWs) that cause motion of the ultrasound transducer assembly, biasing SWV measurements. In this paper, we introduce a bone echo correction (BEC) method that uses echoes from bone underlying the tissue of interest as a stationary reference to detect and remove SAW-induced motion artifacts (SAW-MAs). An in vivo experiment on relaxed human biceps showed that uncorrected SWV was 8.6 ± 1.69 m/s, whereas BEC reduced it to 5.1 ± 1.02 m/s, revealing a mean bias of 3.5 m/s due to SAW-MAs. These findings demonstrate the feasibility of BEC for SAW-MA removal, and its potential to improve quantitative monitoring of muscle mechanical properties using wUS-SWEM.