What is MRI?

MRI stands for Magnetic Resonance Imaging. This test provides a means of obtaining images of various parts of your body without the use of x-rays (ionizing radiation). An MR scanner consists of a large and very strong magnet which surrounds the patient. A specialized antenna transmits radiofrequency energy (RF) into the body and then receives the RF signals back. These returning signals are converted into pictures by a computer attached to the scanner. Pictures of almost any part of your body can be obtained at almost any angle.

IS MRI safe?

MRI is safe in the majority of patients although certain patients may not be able to have an MRI. These include people who are extremely claustrophobic and those with implanted medical devices such as certain aneurysm clips in the brain, heart pacemakers, and cochlear (inner ear) implants. Also, those people with pieces of metal close to or in an important organ (such as the eye) may not be scanned. Please inform the technologist if you are pregnant or breast-feeding. There are a few additional safety considerations and some exceptions based on individual circumstances.

What will the MRI experience be like?

You will be asked to lie still on a table that will move your body into the center of the magnet. Prior to the table moving, you will be offered either earplugs to reduce the noise you hear or stereo headphones to listen to your favorite music. You will hear some "knocking" noises while the scanner is preparing for scanning and taking the pictures. You may also feel some vibration during the knocking noise and some slight movement of the table during the examination.

Some patients will be given an injection in a vein in their arm containing a substance that improves certain types of images. This substance, called gadolinium, is a very safe contrast agent and is unrelated to the iodine used for CT scans and kidney x-rays.

What are the uses and advantages of an MRI?

MRI scanners are good for looking at the non-bony party, or "soft tissues" of the body. In particular, the brain, spinal cord, and nerves are seen much more clearly with MRI than regular x-rays and CT scans. Also, MRI scans are commonly used to look at knees and shoulders following injury to assess the muscles, ligaments, and tendons. Additionally, a MR scanner uses no x-rays or other radiation and is non-invasive.