Power Doppler imaging: principles and applications.

Power Doppler Imaging (PDI) is a promising new sonographic technique for evaluating the vascular system. PDI uses special processing to display the amplitude or strength of the Doppler signal, rather than velocity and directional information as in conventional color Doppler. This allows a much greater sensitivity in detecting small vessels and slow-moving blood. Currently PDI is being used only in conjunction with color Doppler, but it has proven valuable in many applications.