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Updated: Jun 25, 2026

Functional Transcranial Doppler Ultrasound for Monitoring Cerebral Blood Flow
Published on: March 15, 2021
Transcranial Doppler series. Part I: Understanding neurovascular anatomy
Heather A Nicoletto1, Marilyn H Burkman
1Neurodiagnostic Laboratory, Duke University Hospital, Durham, North Carolina, USA.
Abstract:
Transcranial Doppler (TCD) is an ultrasound study that evaluates the blood flow in the brain and is considered by many to be the most difficult vascular study to perform. The circle of Willis is the group of vessels that are insonated with TCD. Knowledge of the arteries that comprise the circle of Willis, the origins of these vessels, and their vessel segments can make the test easier to perform. The technologist performing the TCD must also be aware that the circle of Willis is not complete in approximately 50% of all cases. Knowledge of the various anomalies will help a technologist understand why they may not be able to insonate a vessel.
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