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MRI (magnetic resonance imaging) is a test that uses a magnetic field and pulses of radio wave energy to make pictures of the organs and structures inside the body. An MRI can give your doctor information about your knee, the bones around it, and the tissues around it, such as cartilage, ligaments, and tendons.
When you have an MRI, you lie on a table and the table moves into the MRI machine.
An MRI of the knee can help find problems such as damage to the ligaments and cartilage around the knee. The MRI also can look for the cause of unexplained knee pain, the knee giving out for no reason, or infections in or around the knee.
If you are over 55 years old, an MRI of the knee is not the best test when checking for osteoarthritis. For most people over 55 years old, your doctor can find knee osteoarthritis using your history, a physical examination, and regular x-rays. Most people don’t need an MRI to diagnose osteoarthritis. It is important for your doctor to use the right test for the right problem. Ordering MRI scans that are not needed can:
In general, there's nothing you have to do before this test, unless your doctor tells you to.
Tell your doctor if you get nervous in tight spaces. You may get a medicine to help you relax. If you think you'll get this medicine, be sure you have someone to take you home.
You won't have pain from the magnetic field or radio waves used for the MRI test. But you may be tired or sore from lying in one position for a long time.
If a contrast material is used, you may feel some coolness when it is put into your IV.
In rare cases, you may feel:
The test usually takes 30 to 60 minutes but can take as long as 2 hours.
There are no known harmful effects from the strong magnetic field used for an MRI. But the magnet is very powerful. It may affect any metal implants or other medical devices you have.
Contrast material that contains gadolinium may be used in this test. But for most people, the benefit of its use in this test outweighs the risk. Be sure to tell your doctor if you have kidney problems or are pregnant.
There is a slight chance of an allergic reaction if contrast material is used during the test. But most reactions are mild and can be treated using medicine.
If you breastfeed and are concerned about whether the contrast material used in this test is safe, talk to your doctor. Most experts believe that very little dye passes into breast milk and even less is passed on to the baby. But if you are concerned, you can stop breastfeeding for up to 24 hours after the test. During this time, you can give your baby breast milk that you stored before the test. Don't use the breast milk you pump in the 24 hours after the test. Throw it out.
Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse advice line (811 in most provinces and territories) if you are having problems. It's also a good idea to keep a list of the medicines you take. Ask your doctor when you can expect to have your test results.
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Adaptation Date: 5/20/2022
Adapted By: Alberta Health Services
Adaptation Reviewed By: Alberta Health Services
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