Bessel Function-Apodized Beams Improve Axial Range for Pointwise Shear Elasticity Estimation with Double-Profile Intersection (DoPIo) Elastography

Double-profile intersection (DoPIo) ultrasound can quantitatively estimate the shear elasticity of tissue at positions on-axis to regions of focused acoustic radiation force impulse (ARFI) excitations. However, previous implementations of DoPIo suffered from poor precision in elasticity estimates away from the focal depth, limiting the spatial range where the technique may be deployed. We hypothesized that a planar ARFI excitation with a Bessel function apodization, a technique initially employed for nondiffractive shear wave generation, would improve the axial extent where DoPIo-based elasticity estimates may hold. We demonstrated a DoPIo acquisition based on a Bessel excitation in silico and compared its performance against an equivalent simulation based on a focused excitation. The use of Bessel push and track beams led to more accurate elasticity estimates over a larger axial range, with the greatest improvements in stiffness accuracy by Bessel versus focused beams occurring 5 mm below the linear transducer array’s elevational focus. Thus, DoPIo estimation of shear elasticity benefits from the use of Bessel-apodized push and track beams.