3D elasticity imaging with acoustic radiation force

Acoustic radiation force impulse (ARFI) based elasticity imaging methods have been under development for the past 15 years, and both qualitative on-axis (ARFI imaging) and quantitative shear wave speed (SWEI) methods have been introduced into the commercial market. On-axis methods employ less processing and provide higher spatial resolution, whereas SWEI methods employ reconstruction algorithms that afford higher contrast and provide quantitative estimates of the underlying material stiffness. Each approach can be optimized through custom beam sequences and processing algorithms for specific clinical applications. We discuss three specific applications herein: 1) hepatic fibrosis and steatosis staging through SWEI, 2) 3D SWEI for characterizing material anisotropy, and 3) 3D prostatic SWEI and ARFI imaging.