Aperture-domain processing and its applications in ultrasound imaging: a review

This paper provides a review of advanced algorithms for ultrasound image formation and signal processing that are based on aperture-domain data (i.e. the data recorded by individual channels prior to beam summation). First aperture-domain data are defined and their properties described, then two specific examples of phase-aberration correction and vector velocity estimation are presented. For phase-aberration correction, sidelobe-reduction techniques based on the coherence of the received aperture-domain data were tested with clinical breast data; the mean improvements in the contrast and contrast-to-noise ratios were 6.9 dB and 23.2 per cent, respectively. For flow estimation, a conventional scanner can only estimate the flow velocity parallel to the beam axis. The proposed flow estimation technique uses aperture-domain data for two-dimensional flow-velocity estimation. The experimental results demonstrate that the estimation errors for the proposed technique are 2.18 per cent and 18.11 per cent in the axial and lateral velocity components, respectively. Other applications in which aperture-domain data can be used are also discussed.