How is vascular flow assessed with Ultrasound?
Flow within vessels is detected and displayed with the use of color and spectral Doppler imaging. Color Doppler US with pulsed spectral display allows for the presence or absence of flow to be displayed (as a color) as well as the direction, velocity, and character of the blood flow. The Doppler spectral display is the waveform in a vessel that depicts both the speed and direction of blood flow (i.e., velocity). By convention, the waveform for blood flowing toward the transducer is depicted above the zero velocity baseline, and the color in the vessel is displayed as red. In contrast, the waveform for blood flowing away from the transducer is displayed below the baseline, and the color in the vessel is displayed as blue.