Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) is a common tool for diagnosing MS. The majority of people with MS have abnormal MRIs. MRIs of both the brain and spinal cord can be helpful in looking for signs of MS.
MRI machines use giant magnets to create magnetic fields. These fields make it possible to obtain high-quality images. MRIs do not involve radiation like computed tomography (CT) or x-ray images.
What happens during an MRI scan?
The MRI machine is usually a donut-shaped tube. Depending on what area is being imaged, a person’s head may be inside the tube. The tube is thin, but still has plenty of space for air. However, because it is a small space, some people may feel anxious during the scan. This is especially the case if they are scared of enclosed spaces.
If you have anxiety during MRI scans, your doctor may recommend taking anti-anxiety drugs. Also, because the machine has a big magnet, all metal must be taken off beforehand. This includes jewelry, hearing aids, and eyeglasses.
The MRI process can be very loud. In some cases, you may be given ear plugs to help drown out the noise. The noises are often described as loud banging sounds, which can be scary if unexpected.
There is an MRI technician monitoring the scan at all times. There are speakers inside the machine so that you can hear and talk to the technician at all times. The scan may take 45 minutes or more to complete.
MRI with contrast
In some cases, you may be given contrast before the MRI. Contrast is used to help look for areas of active damage in the brain and spinal cord. Contrast material is often made out of gadolinium. It highlights specific structures in the body on imaging. Your doctor will tell you if you need contrast before the study.
A person can drink contrast orally or it can be given through an IV. In some cases, both forms of contrast are used. Contrast can be damaging to the kidneys if a person takes too much of it. Studies that use contrast are often broken up over several days. People with kidney issues may not be able to receive contrast at all. However, newer forms of contrast that are safe for those with kidney disease are becoming more available.1
Who cannot have an MRI scan?
Because there is no radiation used, MRIs are very safe. MRIs are often used in children and pregnant women when imaging is needed. However, there are other factors to consider before getting an MRI. It is still possible for you to have trouble with the magnet and/or the contrast.
As mentioned, the MRI machine uses a giant magnet. For many, this does not cause a problem as any metal they have on their body is removable (like earrings). But in some cases, metal may be harder or impossible to remove.
For this reason, people with implanted pacemakers for the heart and cochlear implants for the ears sometimes cannot undergo an MRI scan. People with metal surgical clips and implanted metal plates or screws also cannot be scanned. 2 If you have any metal in your body and are concerned about whether an MRI is safe for you, check in with your doctor first.
As mentioned, contrast is helpful for MRI scans and safe in most cases. People who have had an allergic reaction to contrast with anaphylaxis should not receive contrast again.
Anaphylaxis includes swelling of the airway, causing severe difficulties in breathing, very low blood pressure, and/or severe skin reactions (itching, hives, or changes in skin color). These reactions often happen minutes after an exposure and require immediate medical care.
Talk with your doctor about any allergies you have prior to receiving contrast.