MRI: What To Expect

When you are having unknown health issues, your physician may recommend you get an MRI (magnetic resonance imaging.) Here is a basic primer on what you need to know about this important diagnostic tool.

What Is An MRI?

An MRI uses pulses of radio of radio waves combined with a magnetic force field to develop a picture of your internal body structures and organs. An MRI can provide more information and greater detail than an x-ray, ultrasound, or CT (computed tomography) can.

How Is An MRI Prepared For?

An MRI isn't right for everyone. Because of its very powerful magnet, patients who have any metal in their body cannot be given a full MRI scan. Cardiac patients who have had a coronary artery stent or pacemaker put in, those with artificial limbs, metal dental braces, or pins to repair broken bones, or a cochlear implant for the hearing impaired are not good MRI candidates. Even some cosmetic procedures, such as permanent eyeliner tattoos, or the birth control intrauterine device (IUD) prohibit the use of an MRI, so make sure you tell your doctor everything regarding your health history.

Most patients can eat or drink normally before the procedure, however if you are having your bile ducts imaged, you will be asked to abstain from liquids for a few hours before the scan. The procedure itself can take up to 90 minutes, so you won't want to drink too much prior to the procedure.

You will need to remove any jewelry, piercings, metal hair accessories, barrettes, hearing aids, and dentures. If you wear a wig, it will need to be removed as well as it can contain metal. Wear clothing without any metal zippers, buckles, or clasps. A pair of sweatpants and a simple t-shirt is ideal, although you may be asked to change into a hospital gown.

What Happens During An MRI?

When you have an MRI, your entire body is put on a special bed that then goes inside a big machine. The machine has an extremely powerful magnet. Sometimes a contrasting agent, usually gadolinium chelates, will be used to increase visibility. This involves an injection of dye, allowing areas like blood vessels to be easily seen. You may be put in head first or feet first, depending on which area needs to be scanned. Some people are extremely claustrophobic, afraid of confined spaces. Your doctor can give you a mild sedative to relax you if this is a problem for you. You will need to have someone drive you home afterwards, though.

The MRI technician will go to an enjoining room, where the computer is located. The machine will pass over you as the radiation technician takes the required pictures, and that's it. If you received a contrast dye injection, drink plenty of water to help flush the dye from your body.