Bruce A. McDermott

Adaptive ultrasonic imaging using SONOLINE Elegra

Adaptive correction of the effects of propagation through inhomogeneous tissue is critical to the improvement of current ultrasonic imaging systems. Currently, estimation and correction of time‐delay errors is more feasible than other more sophisticated approaches. Data acquisition, time‐delay estimation and compensation have been implemented on the SONOLINE Elegra system using the system CPU, the Crescendo image processor, and the existing front‐end electronics. Experimental results with this implementation will be reported. The effects of compensating the transmit beam is studied using the waveform similarity factor and single transmit imaging. On an RMI404 phantom plus a 1‐D aberration layer with a 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 to 0.77 mm, and the image contrast improved by 8.5 dB (speckle region is 6 ...

Adaptive ultrasonic imaging using SONOLINE Elegra/sup TM/

Data acquisition, time delay estimation and correction for adaptive imaging are implemented on the SONOLINE Elegra/sup 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.