Fig. 9

Schematic representation of current local speed of sound (SoS) algorithms. a Local speed of sound assessed using the spatial coherence method provides a global value in m/s without a parametric image. A tissue with a low coherence R(m) among transducer elements location (m = 1–128 on this example) would underestimate the speed of sound, whereas a tissue with high coherence would provide the real speed of sound. b Local speed of sound determined with the spatial domain compounding approach provides a parametric map of the speed of sound. Compounding is obtained by insonifying the tissue at different angles θ. See [37] for specific definitions of parameters used in this graph. Figure modified, adapted, and reproduced with permission from [36] and [37]