Transcranial Doppler (TCD) Ultrasound Imaging
A Transcranial Doppler (TCD) exam uses ultrasound to evaluate the blood flow inside the head by examining the basal cerebral arteries. There are three cranial “windows” used to obtain this information. For this test, an ultrasound transducer is placed over the temporal bone (in front of the ear), over the closed eyelid, and at the base of the skull in order to acquire signals. Arteries that can be examined include the middle, anterior and posterior cerebral, ophthalmic and carotid siphon and the vertebral and basilar arteries.
Transcranial Doppler exam using temporal window
Ultrasound image of the Circle of Willis
Doppler ultrasound waveform of flow velocities in the middle cerebral artery
Indications for the Test
• Evaluation of vasospasm secondary to subarachnoid hemorrhage (hospitalized patients)
• Detection of intracranial stenosis secondary to sickle cell disease
• Evaluation of intracranial stenosis/occlusion/thrombosis/dissection
• Detection of collateral flow secondary to stenosis/occlusion of vessels proximal to the circle of Willis
• Evaluation of arteriovenous malformation (AVM) feeding arteries
• Detection of cavernous carotid fistula
• Evaluation of cerebral circulatory arrest (hospitalized patients)
What to Expect
Prior to Test
There is no preparation required.
At the Testing Center
• You will be asked about your medical and surgical history
• You may have your blood pressure taken
• You may be allowed to have a family member or friend with you in the exam room during the test
During the Exam
• You will lie comfortably on a stretcher in the testing room; the lights will be dimmed
• The technologist will apply water soluble gel and place an ultrasound transducer at the temporal area in front of the ear, over the closed eyelid and at the base of the skull.
• Doppler ultrasound amplifies the sound of the blood flow and you will hear a sound like a heartbeat.
• The technologist will remove the gel from your skin using a soft washcloth.
When the Exam is Done
You will be ready to leave depending on the results. If the technologist has critical findings, you will be asked to wait at the facility for further instructions from your doctor after the results are shared. The technologist may need to take more images if requested by your physician.
How Long Will it Take?
• 40 – 60 minutes
Will it Hurt?
• The exam is non-invasive and painless.
• A specialized physician will analyze the images and send a report to your doctor. Your doctor will talk to you about the results and any further tests or treatments.
After the test, call your doctor if you have worsening symptoms.