Calibration of ARFI displacements using diastolic shear wave speeds for estimating systolic elasticity
ARFI displacements have been shown to share an inverse relationship with shear wave speed - based estimates of tissue elasticity. Both ARFI and shear wave elasticity imaging (SWEI) have been used to track the stiffening and softening of myocardium through the cardiac cycle in open-chest, intracardiac, and Langendorff preparations. In transthoracic imaging, induced shear waves have been observed during diastole, but only ARFI displacements have been accurately measured through both diastole and systole. Because ARFI displacements only map relative elasticity, they cannot be directly used to characterize absolute properties. We propose here a method for using diastolic shear wave speeds to calibrate ARFI displacement magnitudes, allowing ARFI displacements to be independently used to quantify shear wave speed throughout the cardiac cycle.
