In TCD, what is the normal direction of flow in the anterior cerebral artery?

In Transcranial Doppler (TCD) ultrasonography, the normal direction of flow in the anterior cerebral artery is away from the beam. This is because the anterior cerebral artery typically branches off from the internal carotid artery and has a flow direction that moves towards the front of the brain, away from the Doppler ultrasound transducer. TCD relies on the Doppler effect where the frequency of sound waves is altered by the motion of blood cells. When blood flow is directed away from the transducer, the frequency shift will be negative, indicating that the flow is in the expected direction for the anterior cerebral artery.

Understanding blood flow patterns in TCD is essential for assessing vascular health and identifying potential abnormalities. Thus, recognizing that the anterior cerebral artery's normal flow is away from the ultrasound beam is key for interpreting TCD findings accurately.