Filter optimization and artifacts estimation for orthogonal frequency division multiplexing with multi line transmission in ultrasound imaging

Multi line transmission (MLT) and orthogonal frequency division multiplexing (OFDM) are two types of approaches which have been individually applied to increase the ultrasound data acquisition rate. Only recently these two techniques have been combined in the search for an additional improvement of the data-acquisition rate. While MLT essentially relies on beams spatial-separations in order to maintain a low interbeam cross- talk and form multiple image-lines simultaneously, OFDM mitigates interbeam cross-talk by assigning to each beam a fraction of the transducer bandwidth. However, generating multiple beams during the transmission phase deteriorates image quality. In particular, imaging artifacts are generated as a consequence of interbeam cross-talk. In this work, results from a filter optimization study are reported and discussed. Data as obtained from wire targets 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.