The development of magnetic resonance imaging in the late 1970s provided a breakthrough of sorts for MS professionals and patients alike. Peering into the brain and spinal cord became possible without risk of injury to the patient. It has also allowed researchers to better understand the role of plaques or lesions in the disease process and to monitor disease activity. MRI has also been helpful in measuring the effectiveness of drug therapies for MS.
MRIs have become an important tool in diagnosing the disease, allowing doctors to identify telltale lesions in the brains and spinal cords of patients who are suspected of having MS. But the complexities of MS prevent the MRI from being a perfect diagnostic indicator. Lesions can appear in the brains of people who do not have MS, and research indicates that about 5 percent of people with MS may have a normal MRI — especially in the early stages of the disease.
How do MRIs target MS?
MRI uses extremely powerful magnetic fields to examine specific compounds, such as water, in the body's tissues. MS lesions have higher than normal water content that can be identified by the MRI, which pinpoints the areas of damage. MRI scans are much more detailed than CT (computerized tomography) scans and x-rays, especially of tissues that are not bone, such as the brain and spinal cord.
MRIs are safe for almost everyone, but it is important to tell your doctor or technician if you have any implant devices, including cochlear implants, a pacemaker, pumps (such as an insulin pump) or metal stabilization rods, plates, or screws from surgery. Not all implant devices are a problem, so don't assume that an MRI is ruled out if you have one.
You will also want to convey whether you are, or may be, pregnant, have tattoos (some tattoos contain metal), wear an intrauterine device, wear dentures, or have been exposed to metal fragments from a war wound or from work in construction.
It is important to make an appointment with your neurologist to discuss the results of your MRI. The doctor will be able to tell you what sort of changes — if any — have occurred in your brain or spinal cord. The time you take to review your MRIs and ask questions helps you to establish a relationship with your doctor and allows you to take an active role in your care.
As noted, a contrast material called gadolinium — a dye — is delivered by intravenous infusion during the scan. The contrast is used to highlight new or active areas of inflammation in the CNS caused by a breakdown of the blood-brain barrier.
How does it work? The gadolinium tends to accumulate in new plaques. The plaques are enhanced by the contrast (or dye) used in MRI. It helps your health care provider separate active lesions from the normal parts of the brain. (Old plaques do not typically enhance with gadolinium.)
Your doctor may order more than one MRI at first — one with contrast and one without. If you are pregnant, or suspect that you are pregnant, it is important to discuss this with your doctor ahead of time. When preparing for an MRI, wear comfortable, loose-fitting clothing. You may also be asked to change into a guest robe; clothes often have metallic fibers or fasteners that can interfere with imaging. You'll also be asked to remove jewelry, eyeglasses, and dental implants. It's best to leave valuables at home.
Patients with kidney problems should talk to their doctors about the use of certain gadolinium-based agents that are used to enhance of the quality of MRI. These patients might be at risk for developing nephrogenic systemic fibrosis, a potentially fatal disease. There is no risk for this condition for people who have normal kidney function.
An MRI looks like a cylindrical tube with a tunnel through the middle. A sliding table moves you into the center of the tube, where you will be asked to hold still while the scans are taken. A loud clicking or banging sound can be heard (about 90 decibels), but earplugs or headphones are given to make the noise less intrusive.
You'll be able to communicate with a technician any time the need arises. (Many people report that they fall asleep during an MRI!) The experience isn't too uncomfortable unless keeping still isn't easy for you. The average time for an MRI scan is about 30 minutes, but the time can vary depending on how many views your doctor has ordered. A radiologist will interpret the results and send a report to your doctor.