High-resolution ultrasound imaging using unified pixel-based and filtered delay multiply and sum beamforming

Unified pixel-based (PB) beamforming has previously been implemented for ultrasound imaging. It was shown to offer significant enhancements in lateral resolution compared to conventional dynamic focusing. Yet, there is still interference from clutter and high sidelobe artefacts that limit the the contrast resolution. In this paper, we propose a combination of the unified pixel-based approach with filtered delay multiply and sum (F-DMAS) as a way of further improving the image quality. This hybrid strategy leverages the spatial coherence among signals collected from regions far from the focal depth. As a result, it helps suppress artefacts from the sidelobes and clutter, which can enhance the contrast resolution on the generated image. The new beamformer is evaluated on both simulation and data from an experimental study. The results show that the proposed approach can significantly improve the lateral resolution and image contrast over the unified PB beamformer. Compared to the F-DMAS, it maintains the high contrast resolution while generating uniform brightness over the entire imaging region.