Short-lag spatial coherence weighted minimum variance beamformer for plane-wave images

The minimum variance (MV) beamformer is an adaptive beamforming technique that can convey enhancements in resolution and contrast and that can be applied to various ultrasonic sequences, including plane-wave imaging. Despite its improvements, it is still susceptible to clutter. The present work uses the short-lag spatial coherence (SLSC) value as a weighting factor in order to improve over conventional MV beamformed images. The proposed SLSC weighted MV beamformer (SLSCw-MV) coherently compounds the different emissions of a plane wave sequence in order to synthesize a tight transmission focus and then computes the SLSC value of signal. This SLSC value is used as a weigthing factor for the beamformed value obtained from the application of the frequency-domain version of the MV beamformer. The proposed method is tested on the 75 plane-wave dataset of the 2016 International Ultrasonics Symposium (IUS) beamforming challenge. Results on simulated and experimental data reveal that SLSCw-MV can convey improvements of 7%-55% in lateral resolution and of 2.5%-13% in contrast with respect to conventional delay-and-sum coherent plane-wave images.