Magnetic resonance angiography

Definition

Magnetic resonance angiography is an MRI exam of the blood vessels. Unlike traditional angiography that involves placing a tube (catheter) into the body, MRA is considered noninvasive.

Alternative Names

MRA; Angiography - magnetic resonance

How the test is performed

You will lie down on a narrow table, which slides into a large tunnel-like tube inside the MRI scanner. You must lie very still during the exam because movement can make the images blurry. The MRI uses very powerful magnets and radio waves to create clear, detailed pictures of the body. Because of the strong magnets, metal objects must stay outside the room. A complete scan may take 1 hour or more. In some cases, a dye (contrast medium) is needed to make blood vessels show up better during the MRI. The contrast medium will be given through a needle (IV) placed in your arm.

How to prepare for the test

Most places require you to wear a medical gown. You must remove all jewelry and all other metal objects, including watches, and leave them outside the exam room.

Make sure you tell the radiologist if you have any of the following:

Metal screws, pins, plates, or staples in your body
Heart pacemaker
Intrauterine device (IUD)
Any type of metal implant in the ear or eye
Bullet fragments in the body
Implanted neurostimulator
Insulin or chemotherapy port

If you are pregnant, be sure to tell your doctor and radiologist before having this test.

Also tell the radiologist if you have kidney disease or are on dialysis, as this may affect whether you can have IV contrast.

How the test will feel

The exam is not painful. Some people may feel some pain when the IV is placed into the arm. In addition, some people may have anxiety because the scanner is very close to the body. If you are claustrophobic, tell your health care provider. You may be given a mild sedative.

The table may be hard or cold. You may wish to ask for a blanket or pillow.

The machine produces loud thumping and humming noises. Ear plugs are usually given to reduce the noise.

Why the test is performed

MRA is used to look at the blood vessels in all parts of the body, including the head, heart, abdomen, lungs, kidneys, and legs.

It may be used to diagnose or evaluate conditions such as:

Arterial aneurysm
Aortic coarctation
Aortic dissection
Stroke
Carotid artery disease
Atherosclerosis of the arms or legs
Heart disease, including congenital heart disease
Mesenteric artery ischemia
Renal artery stenosis (narrowing of the blood vessels in the kidneys)

Normal Values

A normal result means the blood vessels do not show any signs of narrowing or blockage.

What abnormal results mean

An abnormal exam suggests a problem with one or more blood vessels. This may suggest atherosclerosis, trauma, a congenital disease, or other vascular condition.

What the risks are

MR angiography is generally safe. However, people have been harmed in MRI machines when metal was in their body or a metal object was in the room. It is very important to tell your health care provider of any metal implants and to always remove all metal from your body and clothing before the test.

There have been reports of patients with kidney failure developing rheumatological disease after receiving MRI contrast agents.

References

Pennell D. Cardiovascular magnetic resonance imaging. In: Libby P, Bonow RO, Mann DL, Zipes DP, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. St. Louis, Mo: WB Saunders; 2007:chap 17.

Jackson J, Allison DJ, Meaney J. Angiography: principles, techniques, and complications. In: Grainger RC, Allison D, Adam A, Dixon AK, eds. Diagnostic Radiology: A Textbook of Medical Imaging. 5th ed. New York, NY: Churchill Livingstone; 2008:chap 6.

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