High velocity investigation with Multi Line Vector Doppler

Vector methods based on the transmission of Plane Waves (PWs) produce impressive 2D maps of blood velocity. They are based on complex algorithms that process intensively huge amount of data. Producing 2D vector maps in real-time stresses the system hardware, limiting the achievable Pulse Repetition Frequency (PRF) which is frequently insufficient to measure, e.g., the blood velocities in stenoses, which may be higher than 2m/s. This work shows how the Multi Line Vector Doppler (MLVD) method, implemented on ULA-OP 256, overcomes part of the difficulties by using the new ‘Virtual Real-Time’ (VRT) processing architecture. In real-time, channel data are saved in the system memory, while in VRT data are re-processed from the memory as if they were coming from the probe. The ULA-OP 256 calculation power is used in real-time to achieve maximum PRF at the expenses of image quality, while in VRT the maximum image quality is restored as well. Experiments are reported where MLVD is shown capable of investigating flow jets up to 3 m/s with PRF of 16 kHz.