[Procedures in color Doppler ultrasound--comparison of methods]

Various colour flow imaging techniques for diagnostic ultrasound have been reported in the literature, each claiming distinctive performance characteristics for the benefit of the user. The following is a review of the principles of autocorrelation, autoregression (or maximum entropy), and of cross-correlation methods. All three approaches are based on the same principle of physics, i.e. the analysis of echoes backscattered from red blood cells of fluctuating density due to motion, but differ in their sampling requirements and in signal processing. A comparison of major performance features and challenges is given.