What is a Doppler ultrasonography?

direct measurement of blood flow and rates of flow, sometimes performed in conjunction with stress testing (exercise between tests).

Disrupted or obstructed blood flow through the neck arteries may indicate the person is a risk of having a stroke. (Narrowed arterial flow in the legs does not necessarily indicate a risk of stroke.)

Doppler ultrasonography can detect the direction, velocity, and turbulence of blood flow. It is frequently used to detect problems with heart valves or to measure blood flow through the arteries.

A Doppler ultrasonography test showing no restricted blood flow is a normal finding.

The Doppler principle is simply that sound pitch increases as the source moves toward the listener and decreases as it moves away.