MRI - shoulder; Magnetic resonance imaging - shoulder
A shoulder MRI (magnetic resonance imaging) scan is an imaging test that uses energy from powerful magnets and to create pictures of the shoulder area.
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 dozens or sometimes hundreds of images.
Related tests include:
You may be asked to wear a hospital gown or clothing without metal snaps or zippers (such as sweatpants and a t-shirt). Make sure you take off your watch, jewelry, and wallet. Some types of metal can cause blurry images.
You will lie on a narrow table, which slides into a large tunnel-like tube.
Some exams require a special dye (contrast). The dye is usually given before the test through a vein (IV) in your hand or forearm. The dye can also be injected into the shoulder. 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 to 60 minutes, but it may take longer.
How to Prepare for the Test
You may be asked not to eat or drink anything for 4 to 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 (sedative). Your doctor may also 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 in 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 cause errors.
The table may be hard or cold, but you can request 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 lets you speak to someone at any time. Some MRIs have televisions and special headphones to help you pass the time.
There is no recovery time, unless you received medicine to relax. After an MRI scan, you can go back to your normal diet, activity, and medicines.
Why the Test is Performed
MRI is useful for diagnosing and evaluating sports injuries. It can provide clear pictures of parts of the shoulder (such as soft tissues) that are hard to see clearly on CT scans.
Your provider may order this test if you have:
- A mass that can be felt during a physical exam
- An abnormal finding on an x-ray or bone scan
- Shoulder pain and fever
- Decreased motion of the shoulder joint
- Fluid buildup in the shoulder joint
- Redness or swelling of the shoulder joint
- Shoulder instability
- Shoulder weakness
- Shoulder pain and a history of cancer
- Shoulder pain that does not get better with treatment
A normal result means no problems were seen in your shoulder and surrounding tissue in the images.
What Abnormal Results Mean
Some possible causes of abnormal results may be:
- Bone infection (osteomyelitis)
- Broken or fractured shoulder bone
- Bursitis in the shoulder area
- Biceps tear
- Abnormal Osteonecrosis (vascular necrosis)
- Rotator cuff tear
- Rotator cuff tendinitis
- Shoulder inflammation (frozen shoulder)
- Tumor (including cancer)
- Labral tear
- Cyst in the shoulder
This list does not include all possible problems. Talk to your provider with any questions and concerns.
MRI contains no radiation. No side effects from the magnetic fields and radio waves have been reported.
The most common type of contrast (dye) used is gadolinium. It is very safe. Allergic reactions to the substance rarely occur. However, gadolinium can be harmful to people with kidney problems that require dialysis. If you have kidney problems, please tell your provider before the test.
The strong magnetic fields created during an MRI can cause heart pacemakers and other implants not to work as well. It can also cause a piece of metal inside your body to move or shift. Please make sure you do not bring anything that contains metal into the scanner room, it can become projectile and dangerous to you.
Tests that may be done instead of an MRI of the shoulder include:
A CT scan may be preferred in some emergency cases, since it is faster and usually available right in the emergency room.
Hanypsiak B, DeLong JM, Lowe WR. Scapulothoracic disorders. In: Miller MD, Thompson SR, eds. DeLee and Drez's Orthopaedic Sports Medicine. 4th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 57.
Wilkinson ID, Graves MJ. Magnetic resonance imaging. In: Adam A, Dixon AK, Gillard JH, Schaefer-Prokop CM, eds. Grainger & Allison's Diagnostic Radiology. 6th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2015:chap 5.