Magnetic Resonance Imaging (MRI) of the Knee

Knee MRI, MRI of the Knee

Risks

There are no known harmful effects from the strong magnetic field used for MRI. But the magnet is very powerful. The magnet may affect pacemakers, artificial limbs, and other medical devices that contain iron. The magnet will stop a watch that is close to the magnet. Any loose metal object has the risk of causing damage if it gets pulled toward the strong magnet.

Metal parts in the eyes can damage the retina. If you may have metal fragments in the eye, an X-ray of the eyes may be done before the MRI. If metal is found, the MRI will not be done.

Iron pigments in tattoos or tattooed eyeliner can cause skin or eye irritation.

An MRI can cause a burn with some medicine patches. Be sure to tell your doctor if you are wearing a patch.

There is a slight chance of an allergic reaction if contrast material is used during the MRI. But most reactions are mild and can be treated using medicine. Contrast material that contains gadolinium may cause a serious problem (called nephrogenic systemic fibrosis) in people with kidney failure. If you have decreased kidney function or serious kidney disease, tell your doctor before having an MRI scan.

There also is a slight risk of an infection at the IV site if contrast material was used.

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Author:	Maria G. Essig, MS, ELS	Last Updated: March 11, 2009
Medical Review:	Adam Husney, MD - Family Medicine Paul D. Traughber, MD - Radiology
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