Typically, magnetic resonance imaging (MRI) is an outpatient procedure performed at a hospital or clinic. Patients should closely follow their physician’s recommendations when preparing for the test. Normally, patients will be allowed to eat without restriction and to take their usual medications. Once at the facility, patients may be asked to change into a gown or to wear clothing without fasteners, such as a sweatshirt and sweatpants. Women may need to remove their bras due to underwires or metal hooks.

It is important for the patient to remove all personal metal objects (e.g., rings, earrings, necklaces) before the test. In fact, patients may want to leave these objects at home on the day of the test. There should be no metal objects inside the room in which the MRI is being performed.

Certain types of implanted medical devices rule out the use of MRI.  These objects generally include (but are not limited to):

• Pacemakers
• Implantable cardioverter defibrillators (ICDs)
• Artificial hips, knees and other joints (in some cases)
• Inner ear (cochlear) implants
• Titanium implants in the mouth
• Aneurysm clip of the brain
• Neuromuscular stimulators
• Implanted drug infusion pump, such as an insulin pump

MRI may be allowed with other types of medical devices, such as artificial joints and certain types of stents and heart valves. In some cases, a specified period of time must have elapsed between the implant of the device and MRI. Patients with these devices should inform their physician and obtain approval before scheduling an MRI. If patients even suspect that they have a metal device or fragment (such as from an injury) inside their body, an MRI might not be an option. Women with intrauterine devices (IUDs) can safely undergo an MRI procedure.

Some MRIs require the use of a contrast medium (dye). In most cases, it is injected into a vein in the arm or hand shortly before the procedure. For some conditions, it may be swallowed in liquid form. This dye can increase the clarity of the images by making the body’s tissues more responsive to the machine’s magnetic and radio waves. In many cases, MRI is first completed without the dye and a second scan is taken following the dye injection. The patient’s physician will order the appropriate test (e.g., with or without contrast) depending on the condition.