Spatial Coherence Based Beamforming in Multi-Line Transmit Echocardiography

Multi-line transmission (MLT) has recently gained interest for high frame-rate ultrasound imaging in cardiac applications, and several approaches have been proposed to address its main limitation, i.e. the limited contrast due to crosstalk artifacts. In this work, we analyze and compare the MLT imaging performance of four spatial-coherence-based beamformers, i.e. Filtered-Delay Multiply and Sum (F-DMAS), Phase Coherence (PC), Sign Coherence (SC) beamforming and Coherence Factor (CF) weighting. Simulations and experimental phantom acquisitions were carried out with the ULA-OP system using a 2 MHz phased array to scan a 90° imaging sector. Standard focused mode (i.e. Single Line Transmission, SLT) and MLT with 4 simultaneously transmitted beams were implemented. Results demonstrate that higher crosstalk suppression, improved lateral resolution and contrast are achieved by employing any of the analyzed coherence-based methods in MLT imaging as compared to Delay and Sum (DAS). Such beamformers can thus represent a promising solution for cardiac applications, achieving a similar or even better image quality than standard methods, but with higher frame-rate.