Resolution improvements in ultrasound elastography using dynamic focusing

During the past decade, signals from conventional focusing schemes with one or a few focal depths have been used in ultrasound elastography. Echo signals from transducer elements have been delayed and summed coherently only at the focus depths, therefore, elastograms reconstructed from these signals could have limited resolution at the area far away from the focal depths. In this work, dynamic focusing has been used to beamform the echo signals before elastographic reconstruction. The axial and lateral resolution of the elastograms were observed and compared to those reconstructed from the conventional focusing scheme with one focal point. Phantoms with two small hard inclusions at different depths were simulated using finite element method and the echo signals were simulated from these phantoms. The results show that the axial and lateral resolutions of the elastograms were improved after using dynamic focusing scheme.