Inspired by the F-DMAS beamforming in B-mode imaging, this work attempts to address the spatiotemporal sensitivity of the conventional flow imaging techniques with a novel non-linear beamforming approach without the use of any contrast agents and deep learning based methods. The major contributions of this work are as follows.

  1. A novel nonlinear beamforming technique is proposed for ultrasound flow imaging and the first effort towards the application of nonlinear beamforming in flow imaging.
  2. We validate the proposed nonlinear beamformer using typical parabolic flow simulations with a cross-correlation based velocity estimator and an autocorrelation based velocity estimator which are the common velocity estimation techniques in the literature.
  3. Further, the proposed approach has been thoroughly investigated for velocity sensitivity with in-vitro datasets including a rotating disk, air bubble tracking, and flow direction reversal. Finally, we report the in-vivo performance evaluation of the proposed approach for a typical pulsatile flow in a carotid artery dataset.
  4. The results, when compared to the state-of-the-art DAS based flow imaging approaches, suggest that the proposed method provides better spatiotemporal sensitivity towards the flow transients.