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Ultrasonography Test (Transcranial Doppler)

What is a transcranial doppler ultrasound (TCD)?

TCD is a non-invasive ultrasound method used to examine the blood circulation within the brain.

During TCD, sound waves, inaudible to the human ear, are transmitted through the tissues of the skull. These sound waves reflect off blood cells moving within the blood vessels, allowing the radiologist to calculate their speed. The sound waves are recorded and displayed on a computer screen.

Your physician has recommended that you have this test to determine the amount of blood flow to certain areas of your brain. The TCD ultrasound can also be used to monitor blood flow in the brain during surgical procedures.

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.

Before the test

There is no special preparation for the TCD ultrasound.

During the test

  • It is not necessary to change into a hospital gown or remove jewelry.
  • Your ultrasound test is performed by specially trained technologists or registered nurses and interpreted by a board-certified radiologist.
  • You will either lie on a padded examining table or sit in a chair during the test.
  • A small amount of water-soluble gel is applied to the skin over the area to be examined. The gel is usually applied on the back of the neck, above the cheek bone, in front of the ear and over the eyelid. The gel does not harm your skin or stain your clothes.
  • A small device called a transducer is held in place on the skin's surface until the blood flow information has been recorded. There is virtually no discomfort during the test.
  • You will need to keep your head still and avoid talking during the test.
  • The ultrasound takes about 20 to 30 minutes to complete.

After the test

The gel will be wiped off your skin. Your physician will discuss the test results with you.

Are there any side effects?

Studies have shown ultrasound is not hazardous. There are no harmful side effects. In addition, ultrasound does not use radiation, as X-ray tests do.

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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 1/31/2007...#4998