Magnetic Resonance Imaging (MRI)

Factors that can interfere with your test or the accuracy of the results include:

• Pregnancy. An MRI test usually is not done during pregnancy. But MRI may be done to get more information about a possible problem that cannot be seen clearly with ultrasound.
• Medical devices that use electronics, such as a pacemaker or medication infusion pump. The MRI magnet may cause problems with these devices, and that may keep you from having an MRI.
• Medical devices that have metal in them. The metal might make some of the detailed MRI pictures blurry. This may prevent your doctor from seeing the organ that is being looked at. For example, an intrauterine device (IUD) with metal may prevent your doctor from seeing the uterus clearly.
• Inability to remain still during the test.
• Obesity. A person who is very overweight may not fit into standard MRI machines.

Many modern medical devices that do not use electronics—such as heart valves, stents, or clips—can be safely placed in most MRI machines. But some newer MRI machines have stronger magnets. The safety of MRI scans with these stronger MRI magnets in people with medical devices is not known.