High-frame-rate imaging of a carotid bifurcation using a low-complexity velocity estimation approach

In this paper, a 2-D vector flow imaging (VFI) method developed by combining synthetic aperture sequential beamforming and directional transverse oscillation is used to image a carotid bifurcation. Ninety-six beamformed lines are sent from the probe to the host system for each VFI frame, enabling the possibility of wireless transmission. The velocity is estimated using a relatively inexpensive 2-D phase-shift approach, and real-time performance can be achieved in mobile devices. However, high-frame-rate velocities can be obtained by sending the data to a cluster of computers. The objective of this study is to demonstrate the scalability of the method's performance according to the needs of the user and the processing capabilities of the host system. In vivo measurements of a carotid bifurcation of a 54-year-old volunteer were conducted using a linear array transducer connected to the SARUS scanner. The velocities were estimated at a rate of 134 independent frames per second (FPS) to reveal complex flow patterns. A peak frame rate of 2140 FPS can be obtained by generating the images recursively. VFI images are shown during the systolic phase revealing the formation of a vortex in the internal carotid artery. The peak systolic velocity from a range gate in the common tract was 0.76ms
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with a standard deviation (SD) of 6.1%. The mean velocity profile was calculated from the same range gate with an average SD of 7.86%.