What is a transcranial doppler ultrasound?

Transcranial doppler ultrasound (TCD) is a non-invasive ultrasound method used to examine the blood circulation within the brain. Your doctor has recommended that you have this test to determine the amount of blood flow to certain areas of your brain.

During TCD, inaudible (cannot be heard) sound waves are transmitted through the tissues of the skull. These sound waves reflect off blood cells moving within the blood vessels, allowing the radiologist to interpret their speed and direction. The sound waves are recorded and displayed on a computer screen.

TCD ultrasound images help in the diagnosis of a wide range of conditions affecting blood flow to the brain and within the brain.

TCD ultrasound may be used with other diagnostic procedures or by itself.

Last reviewed by a Cleveland Clinic medical professional on 02/07/2017.


  • Radiological Society of North America. Cranial Ultrasound/Head Ultrasound Accessed 2/14/2017.
  • Purkayastha S, Sorond F. Transcranial Doppler Ultrasound: Technique and Application. Semin Neurol. 2012 Sep; 32(4): 411–420.

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