Improved Ultrafast Power Doppler Imaging by Using Spatial and Angular Coherence Factor

Ultrafast power Doppler imaging (uPDI) technique was recently proposed and developed to imaging microvessels for new insights into disease diagnosis. Ultrafast plane wave imaging increases the frame rate to more than 1 kHz, paving the way for uPDI. However, the imaging quality of uPDI is poor due to the unfocused transmission of plane waves, which may affect the diagnosis accuracy based on microvessels. Coherence factor (CF) is a classical adaptive beamformer by utilizing the spatial coherence of signals across channels. In this study, we propose a spatial and angular coherence factor (SACF) beamformer for improved uPDI, which considers the spatial coherence between channels and the angular coherence between different transmit angles sequentially. In-vivo results in contrast-free and contrast-enhanced conditions show the superiority of the proposed SACF method over the conventional delay-and-sum (DAS) and CF beamformers, in terms of improved contrast and resolution, and reduced background noise.