An Acoustic Radiation Force Impulse imaging SNR upper bound with numerical validation and 1.5D ARFI transducer design

Acoustic Radiation Force Impulse (ARFI) imaging techniques have utility in a number of clinical applications, such as lesion detection or diagnosis of liver or prostate disease. In modern ultrasound systems possessing high electronic signal to noise (SNR_ε) levels, the major limiting factor in ARFI image signal to noise (SNR_ARF) performance is echo decorrelation arising from differential motion across the point spread function. In this paper, we present an analytical model for an upper bound on SNRARF beginning with previous work describing theoretical echo decorrelation and a lower bound on displacement estimation variance. Using information gained from this analysis, we propose a new optimized 1.5D ARFI transducer array design that increases the ratio of pushing to tracking beam widths, reduces echo decorrelation and increases SNRARF in comparison with conventional ID arrays currently used for ARFI imaging. The performance of the ID conventional and optimized 1.5D ARFI transducers are compared using a FIELD II and finite element model (FEM) numerical simulation framework. Our simulation framework confirms our analytical expression for an upper bound on SNRARF. Lesion images from our numerical simulations produce a 4.5dB contrast to noise (CNR) improvement with the proposed 1.5D ARFI array.