Motion estimation using common spatial frequencies in synthetic aperture imaging

Correlation processing using fully common spatial frequencies of overlapping subapertures is explored for motion estimation between consecutive excitations in multi-element synthetic aperture imaging. Signals derived from the subset of elements representing common spatial frequencies exhibit significantly higher correlation coefficients than those from signals computed using the entire subaperture. In addition, the correlation coefficient decreases linearly with subaperture separation for complete subaperture signals, but remains nearly constant with subaperture separation if only common spatial frequencies are used. Correlation processing using fully common spatial frequencies is tested on experimental rf data acquired from a diffuse scattering phantom using a 3.5 MHz, 128-element transducer array. The results indicate that common spatial frequencies can be used for correlation processing to minimize motion artifacts in synthetic aperture imaging.