User parameter free approaches to multistatic adaptive ultrasound imaging

Delay-and-sum (DAS) beamforming is the standard technique for ultrasound imaging applications. Due to its data independent property, DAS may suffer from poorer resolution and worse interference suppression capability than the adaptive standard Capon beamformer (SCB). However, the performance of SCB is sensitive to the errors in the sample covariance matrix and the signal steering vector. Therefore, robust adaptive beamforming techniques are desirable. In this paper, we consider ultrasound imaging via applying a user parameter free robust adaptive beamformer, which uses a shrinkage-based general linear combination (QLC) algorithm to obtain an enhanced estimate of the array covariance matrix. We present several multistatic adaptive ultrasound imaging (MAUI) approaches based on QLC to achieve high resolution and good interference suppression capability. The performance of the proposed MAUI approaches is demonstrated via an experimental example.