Towards 3-D tissue doppler ultrafast echocardiography: An in vitro study

The emergence of ultrafast imaging allows new insights into cardiac deformation/motion analysis that could enable new advancements in clinical diagnosis. Several studies showed that a good compromise between the temporal and the spatial resolution can be obtained by transmitting multiple focused beams simultaneously, method referred in literature as MLT (multi line transmit). However, previous investigations on 3D MLT were limited to simulations or retrospective synthetic implementations, and thus cannot be used in dynamic conditions. The objective of this study was to evaluate the performance of MLT on a moving phantom represented by a spinning disk. Images of the in vitro model were acquired using four Verasonics systems synchronized to drive a 32×32 Vermon probe. The Doppler velocities were estimated on volumetric data using an ensemble auto-correlator. The results showed that the images acquired using MLT can provide accurate Doppler velocities (mean relative error in the entire volume = 4.1%). MLT allowed an 8-fold increase in volume rate with preserved Doppler image quality, which could open up new clinical opportunities in cardiac echo imaging.