BB p-DAS, an extension of p-DAS to baseband domain for Doppler imaging

( )Over the last decade, several beamforming algorithms have been proposed to improve both resolution and contrast of ultrasound imaging over the conventional Delay-And-Sum (DAS), such as adaptive approaches, subspace methods, or nonlinear operators. The latter include p-DAS, which operates only on radio-frequency (RF) signals, and BB p-DMAS, a flexible alternative to either RF or IN (in-phase and quadrature) signals (in the baseband domain). BB p-DMAS visually provides the same result as p-DAS on RF but shifts the central frequency of the beamformed signals to p x f(0), which can lead to unwanted aliasing in Doppler imaging. In this work, we introduce BB pDAS, an improved version of p-DAS that operates in the baseband domain and preserves the spectral information centered at fo. We formulated it to prove the strict equivalence with BB p-DMAS in terms of B-Mode image characteristics. We highlighted the advantage of keeping the spectrum of the beamformed signal centered at f(0) with visual examples of color Doppler imaging on a rotating disk.