A broadband MVDR beamforming core for ultrasound imaging

Abstract

The Minimum Variance Distortion less Response (MVDR) beamformer is an attractive alternative to conventional delay and sum (DAS) beamformers in medical ultrasound imaging. However, it is not widely employed in medical ultrasound imaging due to its computational complexity. In this paper, we intend to present a novel broadband MVDR beamformer architecture and its implementation for up to 32 channel ultrasound imaging system. The proposed architecture is based on the subarray MVDR and Dichotomous Coordinate Descent (DCD) iteration based adaptive weight computation. A Field Programmable Gate Array (FPGA) based ultrasound system prototype set up is designed, and the proposed MVDR beamforming Core is emulated on the FPGA. The proposed beamforming core could achieve up to 65.5 fps for a 640 x 480 ultrasound frame. The ultrasound system prototype operates at 20 MHz sampling frequency, and the FPGA implementation resulted in approximately 35% of FPGA resources (Xilinx Kintex-7 410T). Image quality comparisons in terms of Contrast Ration (CR) and Contrast to Noise Ratio (CNR) were performed with MATLAB™ MVDR model ported on the Verasonics™ Vantage-64 ultrasound research platform.