No abstract

-Conventional pulse wave Doppler techniques can only provide one-dimensional blood velocity components parallel to the direction of the beam and conventional focusing provides limited frame rates of about 30-40 frames per second. As a solution to these well known limitations we perform a two-dimensional vector mapping using compounded coplanar oriented plane waves, analogous to vector-Doppler. Our method was tested using Field II simulations of both stationary parabolic pipe flow and computational fluid dynamics determined flow through a patient specific carotid artery. Our results show the ability for this method to provide more discernible representation of the flow dynamics compared with conventional color-Doppler imaging, while maintaining a frame rate of roughly 500 frames per second. Quantitative comparison with known velocity fields provides robust validation and demonstrates error comparable to that found in literature using conventional Doppler measurements. Moreover, this method provides a promising means to quantify quick transitory events and complex flow structures unattainable with clinical color-Doppler.

No abstract

Analysis and quantification of both intracardiac blood flow and myocardial motion by Doppler ultrasound (US) are of major interest to early detect heart failure. Furthermore these medical examinations are becoming part of daily clinical setups. Although noninvasive measures are yielded by conventional US Doppler, these are incomplete since only the velocity components along the US beam direction are captured. In addition, because one usually needs to cover a large sector in cardiac imaging, frame rates (typically < 50 fps) offered by standard focused US are generally too low to fully describe the intracavitary blood flow and tissue motion. For the same last reason, alternate techniques such as speckle tracking and/or echo-PIV (particle image velocimetry) are also currently limited by a reduced frame rate. The objective of this in vitro study was to demonstrate the capability of ultrafast circular wave imaging to provide accurate time-resolved vector flow mapping over a wide deep sector scan. Circular wave imaging was chosen in the context of potential cardiac applications, where wide regions of interest (ROI) are required but only small intercostal acoustic windows are available.

No abstract