Filter optimization for orthogonal frequency division multiplexing combined with multi line transmission for ultrafast ultrasound imaging

Abstract

Multi-line transmission (MLT) and orthogonal frequency division multiplexing (OFDM) are two types of approaches which have been individually applied to increase ultrasound data acquisition rate. Both consist in the simultaneous transmission of several beams to reconstruct multiple image lines at the same time, which, however, implies interbeam cross-talk that deteriorates image quality. In particular, as a consequence of interbeam cross-talk, imaging artifacts are generated. While MLT essentially relies on beams spatial-separations to limit interbeam cross-talk, OFDM mitigates interbeam-cross-talk by assigning to each beam a fraction of the transducer bandwidth. Recently the combination of the two techniques has been tested and shown effective to further boost the data acquisition rate [doi:10.1109/ULTSYM.2018.8580107]. In this work, results from a filter optimization study are reported and discussed. Data as obtained from wire targets and tissue mimicking phantoms have been analysed to asses the impact of filter type, order and bandwidth on key imaging features, i.e., axial resolution, interbeam cross-talk, and artifacts area. The ULA-OP 256 system equipped with a 2.4 MHZ phased array was employed to collect the data.