Ultrasound imaging using modal domain frequency smoothed MVDR beamforming **

Increasing the reliability of ultrasound images can significantly aid clinical diagnosis. Recently, MVDR beamforming has been applied to medical ultrasound imaging and achieved promising results. In this paper, we propose a new method of MVDR beamforming with frequency smoothing in the modal domain. The proposed method de-correlates the signal correlation matrix and reduces interference. With the modal expansion and radially focusing the frequency domain signal, it removes the influence of frequencies on the original received signal before applying frequency smoothing and beamforming to achieve a better speckle reduction ability than previous methods. As examined by simulation, the method provides a better approach to find the optimal weights for the transducers constructing medical ultrasound images, which effectively decreasing the side effects, resulting in a better image quality.