Speed of Sound Imaging with Curvilinear Probes from Full-Synthetic Aperture Data

Speed-of-sound (SoS) estimation is important in abdominal ultrasound for both aberration compensation and liver tissue quantification, and there is need to develop SoS reconstruction methods for curvilinear array geometries. In this work, we directly reconstruct SoS from full-synthetic aperture (FSA) datasets. We first introduce scatterer triangulation from Common-Mid-Point (CMP) gathers acquired with curvilinear probe geometries, where a spatio-temporally filter allows selection of scattering signals from a single azimuth direction. Next we develop a ray-tracing interpolation approach and regularized inversion for ultrasound computed tomography reconstruction in polar geometries. Our method allows direct estimation of both scattering locations and absolute time delays for SoS estimation. Experimental SoS estimation in attenuating phantoms is feasible at depths> 120 mm. Experimental SoS reconstruction is demon-strated in layered abdominal phantoms simulating fatty liver disease stages through aberrating subcutaneous tissue layers.