MRA of the Legs: About This Test

What is it?

MRA (magnetic resonance angiogram) is a type of magnetic resonance imaging (MRI) scan that uses a magnetic field and pulses of radio wave energy to provide pictures of blood vessels inside the body. A standard MRI cannot provide a good picture of the blood vessels and blood flow.

People who have an MRA also may have an MRI.

When you have an MRA, you lie on a table and the table moves into the MRI machine. An MRA is done with the same machine as an MRI.

Why is this test done?

An MRA of the legs is done to look at the blood vessels in the legs. It checks for narrowing (stenosis) and blockage of the arteries. Narrowing of the arteries is called peripheral arterial disease. The test can also be used to help a surgeon prepare for surgery on the arteries of the pelvis and legs.

How can you prepare for the test?

• In general, there's nothing you have to do before this test, unless your doctor tells you to.
• Tell your doctor if you get nervous in tight spaces. You may get a medicine to help you relax. If you think you'll get this medicine, be sure you have someone to take you home

How is the test done?

Before the test

• You will need to remove all metal objects (such as hearing aids, dentures, jewelry, watches, and hairpins) from your body. These objects may be attracted to the powerful magnet used for the test.
• You will need to take off all or most of your clothes, depending on which area is examined. (You may be allowed to keep on your underwear if it's not in the way.) You will be given a gown to use during the test. If you are allowed to keep some of your clothes on, make sure your pockets are empty.
• If you wear a medicine patch, you may need to remove it. The MRI can cause burns with some patches.
• You may be given a sedative if you are nervous or you don't think you can lie still for the test.

During the test

• You may have contrast material (dye) put into your arm through a tube called an I.V.
• You will lie on a table that's part of the MRI scanner.
• The table will slide into the space that contains the magnet.
• Inside the scanner, you will hear a fan and feel air moving. You may hear tapping, thumping, or snapping noises. You may be given earplugs or headphones to reduce the noise.
• You will be asked to hold still during the scan. You may be asked to hold your breath for short periods.
• You may be alone in the scanning room. But a technologist will watch through a window and talk with you during the test.

How does having a magnetic resonance angiogram (MRA) feel?

You won't have pain from the magnetic field or radio waves used for the MRI test. But you may be tired or sore from lying in one position for a long time.

If a contrast material is used, you may feel some coolness when it is put into your I.V.

In rare cases, you may feel:

• Tingling in the mouth if you have metal dental fillings.
• Warmth in the area being checked. This is normal. Tell the technologist if you have nausea, vomiting, a headache, dizziness, pain, burning, or breathing problems.

How long does the test take?

The test usually takes 30 to 60 minutes but can take as long as 2 hours.

What are the risks?

There are no known harmful effects from the strong magnetic field used for an MRI. But the magnet is very powerful. It may affect any metal implants or other medical devices you have.

Risks from contrast material

Contrast material that contains gadolinium may be used in this test. But for most people, the benefit of its use in this test outweighs the risk. Be sure to tell your doctor if you have kidney problems or are pregnant.

There is a slight chance of an allergic reaction if contrast material is used during the test. But most reactions are mild and can be treated using medicine.

If you breastfeed and are concerned about whether the contrast material used in this test is safe, talk to your doctor. Most experts believe that very little dye passes into breast milk and even less is passed on to the baby. But if you are concerned, you can stop breastfeeding for up to 24 hours after the test. During this time, you can give your baby breast milk that you stored before the test. Don't use the breast milk you pump in the 24 hours after the test. Throw it out.

What happens after the test?

• You will probably be able to go home right away. It depends on the reason for the test.
• You can go back to your usual activities right away.