Shoulder MRI scanMRI - shoulder; Magnetic resonance imaging - shoulder
A shoulder MRI (magnetic resonance imaging) scan is a imaging test that uses powerful magnets and radio waves 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.
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-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 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 it 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, 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:
- 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. If you have difficulty lying still or are very nervous, you may receive medicine to relax you. Too much movement can blur MRI images and 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 allows you to speak to someone at any time. Some MRIs have televisions and special headphones that help you pass the time.
There is no recovery time, unless youreceived medicine to relax. After an MRI scan, you can resume your normal diet, activity, and medications.
Why the Test is Performed
MRI is a very useful tool for diagnosing and evaluating sports-related injuries. It can provide clear pictures of parts of the shoulder (such as soft tissues) that are difficult to see clearly on CT scans.
Your doctor 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 dislocation
- Shoulder weakness
- Shoulder pain and a history of cancer
- Shoulder pain that does not get better with treatment
A normal result means your shoulder and surrounding area appear normal.
What Abnormal Results Mean
Abnormal results may be due to:
- Bone infection (osteomyelitis)
- Broken or fractured shoulder bone
- Bursitis in the shoulder area
- Osteonecrosis (vascular necrosis)
- Rotator cuff tear
- Rotator cuff tendinitis
- Shoulder inflammation (frozen shoulder)
- Tumor (including cancer)
This list is not all-inclusive. Consult your health care provider with any questions and concerns.
MRI contains 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 is 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 not to work as well. It can also cause a piece of metal inside your body to move or shift.
Tests that may be done instead of an MRI of the shoulder include:
- Shoulder CT scan
- X-ray of the shoulder
A CT scan may be preferred in some emergency cases, since it is faster and usually available right in the emergency room.
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.
DeLee JC, Drez D Jr, Miller MD, eds. DeLee and Drez’s Orthopaedic Sports Medicine. 3rd ed. Philadelphia, Pa: Saunders Elsevier; 2009:chap 17.
Review Date: 2/19/2011
Reviewed By: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; C. Benjamin Ma, MD, Assistant Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.