Multi transmit beams for fast cardiac imaging towards clinical routine

Multiple-line transmit (MLT) techniques, involving the simultaneous transmission of multiple focused beams into different directions, increase the frame rate without significantly compromising the resolution or contrast. The higher frame rate can facilitate the assessment of regional myocardial deformation or of left ventricular dyssynchrony. However, application in clinical routine is still hindered by the lack of real-time implementations. This paper reports on the first real-time implementation of MLT-based imaging and on a pulse-width modulator for three-level pulsers, so as to transmit complex waveforms like those needed by MLT. Experiments with the ULA-OP 256 research scanner connected to a 128-element phased array probe show that real-time imaging is feasible at up to 212 Hz without significant reduction in image quality or field-of-view, pushing fast MLT cardiac imaging one-step forward to clinical routine.