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 noninvasive.

How the Test is Performed

You may be asked to wear a hospital gown or clothing without metal fasteners (such as sweatpants and a t-shirt). Certain types of metal can cause blurry images.

You will lie on a narrow table, which slides into a large tunnel-shaped scanner.

Some exams require a special dye (contrast). Most often, the dye is given before the test through a vein (IV) in your hand or forearm. The dye helps the radiologist see certain areas more clearly.

During the MRI, the person who operates the machine will watch you from another room. The test may take 1 hour or more.

How to Prepare for the Test

You may be asked not to eat or drink anything for 4 - 6 hours before the scan.

Tell your doctor if you are afraid of close spaces (have claustrophobia). You may be given a medicine to help you feel sleepy and less anxious, or your doctor may suggest an "open" MRI, in which the machine is not as close to the body.

Before the test, tell your health care provider if you have:

Because the MRI contains strong magnets, metal objects are not allowed into the room with the MRI scanner:

How the Test will Feel

An MRA exam causes no pain. If you have problems lying still or are very nervous, you may be given a medicine (sedative) to relax you. Moving too much can blur images and cause errors.

The table may be hard or cold, but you can ask for a blanket or pillow. The machine produces loud thumping and humming noises when turned on. You can wear ear plugs to help reduce the noise.

An intercom in the room allows you to speak to someone at any time. Some scanners have televisions and special headphones that you can use to help the time pass.

There is no recovery time, unless you were given a medicine to relax.

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:

Normal Results

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.

Risks

MR angiography is generally safe. It uses no radiation. To date, no side effects from the magnetic fields and radio waves have been reported.

The most common type of contrast (dye) used contains gadolinium. It is very safe. Allergic reactions to the substance rarely occur. However, gadolinium can be harmful to patients with kidney problems who require dialysis. If you have kidney problems, please tell your health care provider before the test.

The strong magnetic fields created during an MRI can cause heart pacemakers and other implants to not work as well. They can also cause a piece of metal inside your body to move or shift.


Review Date: 5/27/2014
Reviewed By: Deepak Sudheendra, MD, Assistant Professor of Interventional Radiology & Surgery, Hospital of the University of Pennsylvania, Philadelphia, PA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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