Determination of 2-D velocity vectors using color Doppler ultrasound

Color Doppler flow images were obtained from two beam directions, and the velocity vectors in the flow field were computed for each pixel point. The technique was applied to an end-to-side anastomosis model. As expected, the directions of velocity vectors change gradually as flow travels through the anastomosis. Highly skewed velocity profiles along with a stagnant flow region were visualized across the lumen of the host artery. High radial velocity components associated with the secondary flow were clearly revealed about 1-2 diameters downstream from the junction. Based on a single Doppler image, this region with radial flow could be incorrectly integrated as a region with high axial velocities. The vector computation clearly resolved this problem. True velocity magnitudes were then used to create color flow images independent of the Doppler angle