DefinitionAn arm MRI (magnetic resonance imaging) scan is a imaging method that uses powerful magnets and radio waves to create pictures of the the upper and lower arm, including 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 dozens or sometimes hundreds of images.See also:MRIShoulder MRI scan
Alternative NamesMRI - arm; Wrist MRI; MRI - wrist; Elbow MRI; MRI - elbow
How the test is performedYou 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 may take longer.
How to prepare for the testYou 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 clipsCertain types of artificial heart valvesHeart defibrillator or pacemakerInner ear (cochlear) implantsKidney disease or dialysis (you may not be able to receive contrast)Recently placed artificial jointsCertain types of vascular stentsWorked 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 feelAn MRI exam causes no pain. If you have difficulty lying still or are very nervous, you may be given a 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 you can use to help the time pass.There is no recovery time, unless you were given a medicine to relax. After an MRI scan, you can resume your normal diet, activity, and medications.
Why the test is performedThis test provides detailed pictures of the arm. It provides clear pictures of parts of the arm that are difficult to see clearly on CT scans.Your doctor may order this test if you have:A mass that can be felt on a physical examAn abnormal finding on an x-ray or bone scanArm pain and a history of cancerArm or wrist pain that does not get better with treatmentBone infection (osteomyelitis)Bone pain and feverBroken boneDecreased motion or "locking up" of the wrist or elbow jointRedness or swelling of the wrist or elbow joints
Normal ValuesA normal result means your arm appears normal.
What abnormal results meanAbnormal results may be due to:AbscessBursitis of the elbow or wristBroken bone or fractureGanglion cyst in the wristInfection in the boneLigament, tendon, or cartilage injury in the wrist or elbowMuscle damageOsteonecrosis (avascular necrosis)Tumor or cancer in the bone, muscle, or soft tissueConsult your health care provider with any questions and concerns.
What the risks areMRI 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 testThe 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.
Special considerationsTests that may be done instead of an MRI of the arm include:CT scan of the armJoint x-rayA CT scan may be preferred in emergency cases, since it is faster and usually available right in the emergency room.
ReferencesHuber 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.