Power Doppler

Abstract

In contrast to frequency-shift color Doppler imaging (CDI), which indicates blood flow velocity and direction, power CDI (PCDI) visualizes the concentration of moving blood scatterers. It is more sensitive than CDI, relatively angle independent, free of aliasing, more accurate in depicting luminal edges, and better in visualizing the continuity of flow. The reasons for this are to be found not so much in the technology but rather in the inherent nature of an amplitude (or power) signal. Nevertheless, recent technologic advances based on PCDI have considerably expanded its clinical use. Topographic PCDI improves delineation of small adjacent vessels. Three-dimensional ultrasound angiography visualizes complex branching and entire vascular trees. Fractional moving blood volume uses power Doppler data to measure the relative amount of blood perfusing an organ. Ultrasound contrast agents and second harmonic imaging significantly increase sensitivity for PCDI detection of small-volume, low-velocity, and deep flows.