Figure 6.

Matched (a) ARFI and (b) SWEI images of a calibrated elasticity phantom with a 20 mm diameter stiff spherical inclusion. The images were generated from the same dataset, which was obtained with a 4 MHz abdominal imaging array, using parallel receiving beam-forming techniques to monitor the tissue response to each excitation throughout the entire field of view. A total of 88 excitation pulses were located at two focal depths (50 and 60 mm), with a beam spacing of 1 mm. The ARFI image portrays normalized displacement at 0.7 ms after each excitation, whereas the SWEI image portrays reconstructed shear wave speed. The lesion contrast is 0.37 and 0.71 for the ARFI and SWEI images, respectively, and the edge resolution (20–80%) is 1.2 mm (ARFI) and 5.0 mm (SWEI) in the plots from a depth of 50 mm, shown in the bottom row.