FIG. 3.

Shear waves measured at 400 Hz and 1 kHz in a 1% wt agarose gel. The MR sequence used was a gradient echo based elastography sequence with the following imaging parameters: repetition time (TR)=1 sec, echo time (TE)=8 ms at 400 Hz and 5.6 ms at 1 kHz, field of view (FOV)=30 mm×30 mm, slice thickness=1 mm, matrix dimension=128×128 pixels, number of excitations (NEX)=2, gradient amplitude=100 G/cm, and number of bipolar pairs=two at 400 Hz and three at 1 kHz. This demonstrates the feasibility of propagating measurable shear waves at frequencies up to 1 kHz where wavelengths are much smaller, thus improving the faithfulness of the recovery.