Two-dimensional velocity reconstruction strategies for color flow Doppler ultrasound images.

A method for calculating the two-dimensional (2-D) velocity vector flow field from color flow Doppler ultrasound images obtained from two or three steering angles has been recently demonstrated. Various strategies for calculating 2-D vectors from noise-corrupted images obtained at multiple angles are described and compared in the present work. This was achieved by using some simple computer flow simulation models to generate color flow images for various beam steering angles. Velocity vectors were calculated for the entire image, and the vectors are displayed at selected points by superimposing them on a magnitude image. It is shown that such displays help improve the qualitative understanding of images obtained from vessels with complex flow geometry. The bias and variance of four reconstruction methods are compared for stimulated laminar flow in a tube. Based on the simulation results, it was found that the dominant factor that affects the reconstruction accuracy is the angle between the observation directions, and that a simple two component method generally gives as good a performance as the more complex alternatives that were studied.