What is magnetic resonance imaging?
Magnetic resonance imaging (MRI) is a test that produces very clear pictures, or images, of the human body without the use of x-rays. MRI uses a large magnet, radio waves and a computer to produce these images.
Is MRI examination safe?
Yes. The MRI examination poses no risk to the average patient if appropriate safety guidelines are followed.
Post-cardiac surgery patients and patients with the following medical devices can be safely examined with MRI:
- Surgical clips or sutures
- Artificial joints
- Cardiac valve replacements
- Disconnected medication pumps
- Vena cava filters (after 6 weeks for certain types)
- Brain shunt tubes for hydrocephalus
- Metal stents
Some conditions may make MRI examination inadvisable. Tell your doctor if you have any of the following conditions:
- Heart pacemaker
- Cerebral aneurysm clip (metal clip on a blood vessel in the brain)
- Implanted insulin pump (for treatment of diabetes), narcotics pump (for pain medication), or implanted nerve stimulators ("TENS") for back pain
- Metal in the eye or eye socket
- Cochlear (ear) implant for hearing impairment
- Implanted spine stabilization rods
- Severe lung disease (such as tracheomalacia or bronchopulmonary dysplasia)
- Gastroesophageal reflux
- Weight of more than 300 pounds
- Inability to lie on back for 30 to 60 minutes
- Claustrophobia (fear of closed or narrow spaces). Please note: if this condition applies to you, you can receive sedation during the exam if prior arrangements have been made.
How long is the MRI exam?
Allow 2 hours for your MRI exam. In most cases, the procedure takes 40 to 80 minutes, during which several dozen images may be obtained.
Before the exam
Personal items such as your watch, wallet, including any credit cards with magnetic strips (they will be erased by the magnet), and jewelry should be left at home if possible, or removed prior to the MRI scan. Secured lockers are available to store personal possessions.
During the exam
You may be asked to wear a hospital gown during the MRI scan.
As the MRI scan begins, you will hear the equipment making a muffled thumping sound that will last for several minutes. Other than the sound, you should experience no unusual sensations during the scanning.
Certain MRI exams require an injection of a contrast material called gadolinium. This helps identify certain anatomic structures on the scan images.
Please feel free to ask questions. Tell the technologist or the physician if you have any concerns.
After the exam
Generally, you can resume your usual activities and normal diet immediately.
The results of your MRI should be available to your physician within 24 hours after your test, Monday through Friday. Your physician will discuss the test results with you.
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This information is provided by Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 4/2/2010...#4876