Fig. 5.

Spatial-temporal displacement images acquired at different times after the shear wave generation in the ex vivo kidneys: (a) control, (b) 100 pulses, and (c) 1000 pulses. The positive and negative displacements indicate directions of motions toward and away from the imaging probe, respectively. Compared with the shear waves generated in the phantoms, the shear waves generated in the kidneys appeared to be more dispersive and attenuated faster. The shear waves slowed down in the lesion area, resulting in a bent wavefront as shown in panels (b) and (c). The curvature increased with increasing numbers of therapy pulses. The shear waves could not propagate very far into the lesion created with more than 1000 pulses/location. Bright spots, likely cavitation bubbles, were observed in the push region after the pushing beams were delivered (examples indicated by the white arrows).