Magnetic Resonance Imaging (MRI) Of The Knee: How It Is Done

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How It Is Done

A magnetic resonance imaging (MRI) test is usually done by an MRI technologist. The resulting pictures are usually interpreted by a radiologist. However, some other types of doctors, such as an orthopedic surgeon, can also interpret a knee MRI scan.

You will need to remove all metal objects (such as hearing aids, dentures, jewelry, watches, and hairpins) from your body because these objects may be attracted to the powerful magnet used for the test.

You will need to take off all or most of your clothes, depending on which area is examined (you may be allowed to keep on your underwear if it is not in the way). You will be given a gown to use during the test. If you are allowed to keep some of your clothes on, you should empty your pockets of any coins and cards (such as credit cards or ATM cards) with scanner strips on them because the MRI magnet may erase the information on the cards.

During the test, you will lie on your back on a table that is part of the MRI scanner. The table will slide into the space that contains the magnet. A device called a coil may be placed over or wrapped around the area to be scanned.

Some people feel nervous (claustrophobic) inside the MRI magnet. If feeling nervous keeps you from lying still, you can be given a medicine (sedative) to help you relax. Some MRI machines (called open MRI) are made so that the magnet does not enclose your entire body. Open MRI machines may be helpful if you are claustrophobic.

Inside the scanner, you will hear a fan and feel air moving. You may also hear tapping or snapping noises as the MRI scans are taken. You may be given earplugs or headphones with music to reduce the noise. It is very important to hold completely still while the scan is being done. You may be asked to hold your breath for short periods of time.

During the test, you may be alone in the scanner room. However, the technologist will watch you through a window. You will be able to talk with the technologist through a two-way intercom..

If contrast material is needed, the technologist will put it in an IV in your arm. The injection may be given over 1 to 2 minutes.

An MRI test usually takes 30 to 60 minutes but can take as long as 2 hours.

Last updated:	April 10, 2007
Author:	Maria G. Essig, MS, ELS
Reviewed By:	Adam Husney, MD - Family Medicine, Paul D. Traughber, MD - Radiology
Editors:	Susan Van Houten, RN, BSN, MBA, Tracy Landauer