One way of conceptualizing Doppler color flow methods is to recognize its similarity to angiography. It provides a noninvasive "angiogram" of blood flow, where the contrast medium is the moving red blood cells and the detector of this contrast is ultrasound. The complex Doppler ultrasound processing circuitry allows for the detection of movement of these red cells in various directions - forward and backward through the heart. Doppler color flow information, however, is obtained and displayed in a cross-sectional image, making the spatial details of flow and anatomy readily recognizable. In effect, Doppler color flow looks inside the cineangiographic silhouette.
Unlike angiography, Doppler color flow does not depend on dye dilution accumulated over several heartbeats. Rather it displays an abnormal flow jet for each cardiac cycle. This results in the ability to display the differing sizes of regurgitant jets depending on severity. The larger the volume of the regurgitant jet, the larger the size represented on the display.
2004