Combining Delay-Multiply-and-Sum and Covariance Matrix-based Weighting for Synthetic Aperture Ultrasound Imaging

The image quality of synthetic aperture (SA) ultra-sound imaging is often degraded due to low electrical signal-to-noise ratio and clutter and noise, resulting in low contrast and lateral resolution. The delay-multiply-and-sum (DMAS) beam-former has been previously studied in SA imaging to improve image quality in terms of resolution and contrast. However, the resolution and contrast performances obtained by DMAS is not well enough and the speckle variation is noticeable. Therefore, we hypothesize that an appropriate adaptive weighting approach for DMAS can help address this issue. This study combines DMAS with a covariance matrix-based adaptive weighting approach to further improve the imaging performance, and simultaneously enhancing the cyst detectability in SA ultrasound imaging. Results show that the proposed method effectively improves the resolution, contrast, and speckle smoothness of DMAS image in SA imaging.