METHOD FOR MAINTAINING A CONSTANT VELOCITY TO COLOR MAP IN AN ULTRASOUND FLOW IMAGING SYSTEM

The method of the invention employs pulsed Doppler ultrasound signals to color image blood and tissue movement velocities in a body. The method initially images a movement with a transmitted ultrasound signal that manifests a current signal transmission frequency value and a current pulse repetition frequency (PRF) value. Those values exhibit a determined ratio R to each other. Thereafter, in response to an indication by the user that movement is to be imaged at a new depth, the method alters the current transmission frequency to a new frequency to provide improved signal back-scatter from movement at the new depth. Then, the current PRF is adjusted, automatically, to a new PRF value which, when compared to the new transmission frequency, manifests substantially the same determined ratio R that was present between the current transmission frequency and current PRF. The latter step assures that the mapping of movement velocity values to colors is maintained, notwithstanding use of a new transmission frequency.