We make a distinction between directional Doppler ultrasonography and transcranial Doppler ultrasonography.

Directional Doppler ultrasonography is used for the diagnosis of pathological vascular alterations in the large neck veins that could be the cause of circulatory disorders.

Directional Doppler ultrasonography is far from satisfactory as a method for diagnosing the risk of strokes (see Strokes).

We also require information about the blood circulation to the vessels located within the bony cranium that supply the cerebral tissue directly with blood.