A comparison of algorithms for tracking sub-pixel speckle motion

We have previously described Ensemble Tracking, a speckle tracking method that uses parallel receive processing and 2D pattern matching to generate a vector velocity map with high spatial and temporal resolution. Due to the mismatch in axial and lateral spatial frequencies of speckle and limited lateral sampling, Ensemble Tracking requires lateral interpolation to improve lateral velocity resolution. In this paper, we compare three interpolation algorithms for measuring lateral sub-pixel speckle motion: Cubic Spline, Parabolic Fit, and Grid Slopes. Simulation results show that Grid Slopes performs better than Cubic Spline and Parabolic Fit, and is accurate over a wider range of speckle translations