Phantom and in vivo demonstration of swept synthetic aperture imaging
Ultrasound imaging of deep abdominal targets suffers from low lateral resolution due to limited aperture size and low-frequency transmit pulses. We demonstrate phantom and in vivo imaging results using a device that allows a tracked mechanical sweep of a commercially available ultrasound array. The position data and device calibration have sufficient precision to allow coherent combination of the backscattered echoes from array positions separated by up to 56.4 degrees at a radius of 10 cm acquired in a time frame of one second, forming a synthetic aperture significantly larger than the physical footprint of the array. In a wire phantom, an 87.5% reduction in full width at half maximum is achieved using this method compared to a single-position full synthetic aperture acquisition. In addition to increased resolution, a 4.2 dB improvement in contrast and 17.3% improvement in contrast-to-noise ratio were measured in a fetal phantom target. The technique was successfully applied to an in vivo liver study using a 45 degree sweep, improving the visibility of both large anechoic targets and small structures on the order of the resolution cell of a conventional image.
