Improved resolution and crosstalk rejection in Multi-Line Transmit ultrasound imaging using Delay Multiply and Sum beamforming

The frame rate of ultrasound images can be increased by simultaneously transmitting several focused beams along different directions, according to the method called Multi-Line Transmission (MLT). Unfortunately, the interference among beams may generate crosstalk artifacts that can be partially prevented, at the expense of lateral resolution, by applying Tukey apodization on transmission and reception. In this paper we propose to improve the receive crosstalk rejection and the lateral resolution in MLT images by means of the non-linear Filtered Delay Multiply And Sum (F-DMAS) beamformer, which was proved to lower the beam side lobes and to narrow the main lobe. The performance of F-DMAS in MLT is tested and compared to that of standard Delay and Sum (DAS) beamforming with Tukey apodization, both in simulation and experimental phantom image acquisitions. Results show significant improvements in terms of resolution and contrast with a 4-times higher frame rate.