Cerebral Angiography
(Cerebral angiogram, Cerebral arteriogram, Digital Subtraction Angiography [DSA])

erebral angiography is used to image the blood vessels of the brain and the blood flowing through them.  Angiography involves entering a catheter into the body to inject a dye (a contrast medium) into the carotid arteries, the vessels of the neck that lead to the brain.  Then regular x-ray is used to image the dye that is flowing through the blood vessels.  Although cerebral angiography can be used to to investigate many abnormalities, only its relevance to stroke is discussed here.

Why do doctors use cerebral angiography?
Cerebral angiographies show the brain's blood vessels.  Doctors use cerebral angiography to detect abnormalities in the brain's blood vessels, such as narrowing or blockage.  It is usually done after another test (such as a CT scan) has already detected an abnormality. Angiography is useful in detecting and diagnosing acute stroke and is especially beneficial since the images taken through cerebral angiography cannot be taken through other techniques.

What happens during a cerebral angiography?
You will be asked to remove all clothing and jewelry and wear a patient gown before undergoing the procedure.  While you are lying on an x-ray table, a local anesthetic is given, usually in the thigh, where an incision is made.  The catheter (a long, narrow flexible tube) is put into your body through the incision navigated to the carotid arteries, where the dye is injected.

After you are properly placed on the exam table, your head is positioned in the desired field of view, and regular x-ray is used to take pictures of the blood vessels in the brain.  While the procedure is being done, both the technologist and radiologist remain by your side.  Although you are awake during the procedure, a medication may be given to help you relax.  The entire procedure can take from one to two hours to complete.

What are the risks of cerebral angiography?
The use of a catheter in cerebral angiography may cause you some discomfort or pain, although an anesthetic is usually given to help alleviate most discomfort.

There is also a risk of stroke caused by the catheter.  While being navigated through the carotid arteries the catheter could break off a plaque that could block a smaller blood vessel in the brain and lead to stroke.

How does cerebral angiography work?
The basic principle behind cerebral angiography is the same as that of regular x-ray imaging.  As the x-rays pass through the body, they are absorbed at different levels.  The absorption of the x-rays by the injected dye allows the blood vessels in the brain to be imaged.  The differences in absorption become one of many images detected by a camera, which finally become a “movie” of the blood flow (and the flow of the intravenous dye) through the vessels.

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