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Magnetic Resonance Angiogram (MRA)
A magnetic resonance angiogram (MRA) 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. In many cases MRA can provide information that can't be obtained from an X-ray, ultrasound, or computed tomography (CT) scan.
MRA can find problems with the blood vessels that may be causing reduced blood flow. With MRA, both the blood flow and the condition of the blood vessel walls can be seen. The test is often used to look at the blood vessels that go to the brain, kidneys, and legs. Information from an MRA can be saved and stored on a computer for further study. Photographs of selected views can also be made.
During MRA, the area of the body being studied is placed inside an MRI machine. Contrast material is often used during MRA to make blood vessels show up more clearly.
Why It Is Done
A magnetic resonance angiogram (MRA) is done to look for:
- A bulge (aneurysm), clot, or the buildup of fat and calcium deposits (stenosis caused by plaque) in the blood vessels leading to the brain.
- An aneurysm or tear (dissection) in the aorta, which carries blood from the heart to the rest of the body.
- Narrowing (stenosis) of the blood vessels leading to the heart, lungs, kidneys, or legs.
How To Prepare
- 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 It Is 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 long the test takes
The test usually takes 30 to 60 minutes but can take as long as 2 hours.
How It Feels
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.
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.
The radiologist may talk to you about the results of your MRA right after the test. Complete results are usually ready for your doctor in 1 to 2 days.
The blood vessels look normal and the blood flow through them is not reduced or stopped. No blood clots or large plaque buildup is seen.
Blood vessel walls are normal. No bleeding, abnormal collections of fluid, blockage in the flow of blood, or bulges in the blood vessels (aneurysms) are seen.
Partial or complete blockage of a blood vessel may be seen. Blockage may be caused by a blood clot, the buildup of fat and calcium deposits (plaque), or narrowing (stenosis) of the blood vessel.
A bulge (aneurysm) in the blood vessel wall may be seen. Damage to the wall of a blood vessel may be seen.
Conventional angiogram or a CT angiogram (computed tomography angiogram) may be needed after MRA if a problem, such as an aneurysm, is found or if surgery may be needed.
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