A signal/noise analysis of quasi-static MR elastography

In quasi-static magnetic resonance elastography, strain images of a tissue or material undergoing deformation are produced. In this paper, the signal/ noise (S/N) ratio [SNR] of elastographic strain images, as measured by a ph ase-contrast technique, is analyzed. Experiments are conducted to illustrat e how diffusion-mediated signal attenuation limits maximum strain SNR in sm all displacement cases, while the imaging point-spread function limits larg e displacement cases. A simple theoretical treatment agrees well with exper iments and shows how an optimal displacement encoding moment can be predict ed for a given experimental set of parameters to achieve a maximum strain S NR. A further experiment demonstrates how the limitation on strain SNR pose d by the imaging point-spread function may potentially be overcome.