Adaptive ultrasonic imaging using SONOLINE ElegraTM

Data acquisition, time delay estimation and correction for adaptive imaging are implemented on the SONOLINE Elegra^TM system using the system CPU, the Crescendo(TM) processor, and the existing front-end electronics, with no hardware modifications. With the current implementation, phase aberration correction takes about 2 seconds from activation to completion. The effects of compensating the transmit beam are studied using the waveform similarity factor and single transmit imaging. On a scattering phantom plus a 1-D aberration layer with an rms time fluctuation of 40 ns and correlation length of 5 mm, the waveform similarity factor of randomly scattered waveforms improved from 0.362 to 0.477 by iteration. Correspondingly, the -20 dB lateral resolution improved from 1.62 mm to 0.77 mm, and the image contrast improved by 8.5 dB (the speckle region is 6 dB brighter while the echo-free region is 2.5 dB darker). Experiments with a 2-D aberration layer and with a special phase aberration phantom showed less image improvements. Preliminary body scan trials with adaptive imaging showed improved image contrast and details in some cases but the results are mixed and influenced by such factors as isoplanatic patch size and complex scattering structures