A Study of Double-Stage DMAS and p-DMAS for Their Relation in Baseband Ultrasound Beamforming

Abstract

Delay-multiply-and-sum (DMAS) imaging is capable of suppressing clutter interference by introducing spatial coherence of received channel data into the beamforming process. Recently, double-stage DMAS beamforming (DS-DMAS) has been proposed by firstly calculating the column sum of auto-covariance matrix and then applying DMAS in the second stage to further highlight the channel coherence. In contrast, p-DMAS beamforming emphasizes the spatial coherence by adopting a single-stage p-th-root magnitude scaling of the channel signal and p-th-power restoration after channel sum. Though their implementation differs, DS-DMAS and p-DMAS produce visually similar image quality. In this study, the relation between DS-DMAS and p-DMAS is analytically demonstrated and verified using simulations and experiments. Results indicate that DS-DMAS beamforming is virtually equivalent to p-DMAS with p = 3 particularly when high coherent target such as wire reflectors are being imaged. Reconstructed B-mode image and corresponding quantitative metrics also suggest high similarity between DS-DMAS and p-DMAS for speckle-generating object. For numerical B-mode image, their absolute difference is below −43.5 dB for wire reflectors and −42.6 dB for pure speckle phantom. Due to their virtually equivalent performance, p-DMAS beamforming is a better alternative than DS-DMAS in terms of computational complexity.