MRI

Magnetic resonance imaging (MRI) is a medical imaging technique that uses a magnetic field and computer-generated radio waves to create detailed images of the organs and tissues in your body. Most MRI machines are large, tube-shaped magnets. When you lie inside an MRI machine, the magnetic field inside works with radio waves and hydrogen atoms in your body to create cross-sectional images — like slices in a loaf of bread.

MRI is a noninvasive way for a medical professional to examine your organs, tissues and skeletal system. It produces high-resolution images of the inside of the body that help diagnose a variety of conditions.

Because MRI uses powerful magnets, the presence of metal in your body can be a safety hazard if attracted to the magnet. Even if not attracted to the magnet, metal objects can distort the MRI images. Before having an MRI exam, you'll likely complete a questionnaire that includes whether you have metal or electronic devices in your body. Unless the device you have is certified as MRI safe, you might not be able to have an MRI . Devices include: Metallic joint prostheses. Artificial heart valves. An implantable heart defibrillator. Implanted drug infusion pumps. Implanted nerve stimulators. A pacemaker. Metal clips. Metal pins, screws, plates, stents or surgical staples. Cochlear implants. A bullet, shrapnel or any other type of metal fragment. Intrauterine device. If you have tattoos or permanent makeup, ask whether it might affect your MRI . Some of the darker inks contain metal. Before you schedule an MRI , tell your doctor if you think you're pregnant. The effects of magnetic fields on an unborn baby aren't well understood. An alternative exam may be recommended, or the MRI may be postponed. Also tell your doctor if you're breastfeeding, especially if you're to receive contrast material during the procedure. It's also important to discuss kidney or liver problems with your doctor and the technologist, because problems with these organs might limit the use of injected contrast agents during your MRI scan.

Before an MRI exam, eat as you would normally and continue to take your usual medicines, unless you're told otherwise. You will typically be asked to change into a gown and to remove things that might affect the magnetic imaging, such as: Jewelry. Hairpins. Eyeglasses. Watches. Wigs. Dentures. Hearing aids. Underwire bras. Cosmetics that contain metal particles.