Hybrid adaptive/nonadaptive beamforming for ultrasound imaging

We propose and evaluate a simple yet effective technique of combining nonadaptive and adaptive beamforming methods aimed to achieve high quality of ultrasound images at low computational cost. Our hybrid beamformer automatically switches between nonadaptive and adaptive beamforming of input data vectors, based on the outcome of the comparison of the input coherence factor against a certain threshold. For illustrative purposes, we used the delay-and-sum (DAS) beamformer as an example of a nonadaptive method, while the Generalized Sidelobe Canceller (GSC) and Adaptive Single Snapshot Beamformer (ASSB) served as two examples of an adaptive method. We have applied our technique to simulated ultrasound images of a 12-point phantom and a point-scattering-cyst phantom, demonstrating substantial computational savings without a significant degradation in the image resolution and contrast, in comparison to the standard GSC-based or ASSB-based beamforming methods.