Arm MRI scan

Definition

An arm MRI (magnetic resonance imaging) scan uses strong magnets to create pictures of the the upper and lower arm. This may include the elbow, wrist, hands, fingers, and the surrounding muscles and other tissues.

It does not use radiation (x-rays).

Single MRI images are called slices. The images can be stored on a computer or printed on film. One exam produces many images.

Alternative Names

MRI - arm; Wrist MRI; MRI - wrist; Elbow MRI; MRI - elbow

How the Test is Performed

You will wear a hospital gown or clothes without metal zippers or snaps (such as sweatpants and a t-shirt). Some types of metal can cause blurry images.

You will lie on a narrow table that slides into a large tunnel-like scanner.

Some exams use a special dye (contrast). Most of the time, you will get the dye through a vein in your arm or hand before the test. 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 most often lasts 30-60 minutes, but may take longer.

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. 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:

• Brain aneurysm clips
• Certain types of artificial heart valves
• Heart defibrillator or pacemaker
• Inner ear (cochlear) implants
• Kidney disease or dialysis (you may not be able to receive contrast)
• Recently placed artificial joints
• Certain types of vascular stents
• Worked with sheet metal in the past (you may need tests to check for metal pieces in your eyes)

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

• Pens, pocketknives, and eyeglasses may fly across the room.
• Items such as jewelry, watches, credit cards, and hearing aids can be damaged.
• Pins, hairpins, metal zippers, and similar metallic items can distort the images.
• Removable dental work should be taken out just before the scan.

How the Test Will Feel

An MRI exam causes no pain. You will need to lie still. Too much movement can blur MRI images and cause errors.

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

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

There is no recovery time, unless you were given a medicine to relax. After an MRI scan, you can return to your normal diet, activity, and medicines.

Why the Test is Performed

This test provides clear pictures of parts of the arm that are hard to see clearly on CT scans.

Your doctor may order this test if you have:

• A mass that can be felt on a physical exam
• An abnormal finding on an x-ray or bone scan
• Arm pain and a history of cancer
• Arm or wrist pain that does not get better with treatment
• Bone infection (osteomyelitis)
• Bone pain and fever
• Broken bone
• Decreased motion or "locking up" of the wrist or elbow joint
• Redness or swelling of the wrist or elbow joints

Normal Results

A normal result means your arm looks okay.

What Abnormal Results Mean

Abnormal results may be due to:

• Abscess
• Bursitis of the elbow or wrist
• Broken bone or fracture
• Ganglion cyst in the wrist
• Infection in the bone
• Ligament, tendon, or cartilage injury in the wrist or elbow
• Muscle damage
• Osteonecrosis (avascular necrosis)
• Tumor or cancer in the bone, muscle, or soft tissue

Talk to your health care provider if you have questions and concerns.

Risks

MRI contains no radiation. There have been no reported side effects from the magnetic fields and radio waves.

The most common type of contrast (dye) used is gadolinium. It is very safe. Allergic reactions to the substance are rare. However, gadolinium can be harmful to people with kidney problems that need 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. It can also cause a piece of metal inside your body to move or shift. For safety reasons, please don't bring anything that contains metal into the scanner room.

Considerations

Tests that may be done instead of an MRI of the arm include:

• CT scan of the arm
• Joint x-ray

A CT scan may be preferred in an emergency. The test is faster than MRI and often available in the emergency room.

References

Huber FG. Arm. In: DeLee JC, Drez D Jr, Miller MD, eds. DeLee and Drez’s Orthopaedic Sports Medicine. 3rd ed. Philadelphia, Pa: Saunders Elsevier; 2009:chap 18.

Grainger RG, Thomsen HS, Morcos SK, Koh DM, Roditi G. Intravascular contrast media for radiology, CT, and MRI. In: Adam A, Dixon AK, eds. Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging. 5th ed. New York, NY: Churchill Livingstone; 2008:chap 2.

Wilkinson ID, Paley MNJ. Magnetic resonance imaging: basic principles. In: Grainger RC, Allison D, Adam, Dixon AK, eds. Diagnostic Radiology: A Textbook of Medical Imaging. 5th ed. New York, NY: Churchill Livingstone; 2008:chap 5.

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