Magnetic resonance imaging (MRI) is a noninvasive test used to help diagnose MS. A series of MRIs can monitor the activity of MS in the brain and spinal cord, particularly to detect how the affected areas change over time. Often, a MRI can detect changes even though an individual is not experiencing symptoms. Health care professionals can review the results of the MRI to determine if there are new areas of change (called lesions). The MRI can provide clues to how changes might affect the individual with MS. The MRI can also show overall disease activity.
The MRI Machine
The MRI machine is a large magnet shaped like a “doughnut”. The patient lies in the “hole of the doughnut” and a radio wave is sent into the field of the magnet. When the radio rave hits the magnetic field, it makes a slight noise. The loud noise that patients hear while in the machine is the sound of many radio waves entering the magnetic field. An antenna placed close to the patient transmits the radio waves received from the machine to a computer. The computer analyzes the signals and creates a black and white image of the body. The MRI provides many different views and photographic “slices” (cross-sections) of areas under examination. Sometimes, to enhance the photographic image, physicians order a MRI with dye. This refers to the process of inserting an intravenous needle (IV) in the arm of the patient, and circulating a nonpoisonous dye throughout the bloodstream. This dye enhances the images read by the computer.
The MRI Test Procedure
If you have MS, you are likely familiar with the MRI test procedure. During a MRI test, the individual lies on a table that moves into a tube-like structure. It is important to lie still. The technician may provide earplugs, because once inside the machine, there are loud noises that mimic a jackhammer. If you are not offered earplugs, ask for them. Some places offer an “open” MRI that does not have the narrow, tube-like space. Some physicians, however, feel that the “closed” MRI provides better results.
The length of time needed for a MRI varies from person to person. Usually, the technician performing the test will talk to you through a microphone and provide encouragement if you are uncomfortable, or tell you how much time remains, etc. Discomfort associated with having a MRI is minimal but may include 1) loud noise, 2) feeling uncomfortable or closed in within the tube-like space, and 3) insertion of the needle into the arm for injection of the dye. Understanding the importance of having the MRI can often help reduce any feelings of fear. Some people prefer mild sedation while having a MRI. This is something you should discuss with your health care provider.
It is important to understand that a MRI is not the only way to diagnose MS. However, a MRI is very helpful when used with other tests, to help determine new cases of MS. In addition, MRI is often used to monitor disease activity in patients with established MS. The MRI can show the development of new damage as it occurs over time. It is important to monitor MS changes with a series of MRIs. The physician or radiology technician who reads a MRI uses a set of accepted and established guidelines to diagnose MS. Along with your medical history, your physician will use results from your MRI to aid in the diagnosis and treatment of MS.
Last Updated: October 2009