Magnetic Resonance Imaging
Reviewed by: HU Medical Review Board | Last updated: March 2023
Magnetic resonance imaging (MRI) is a common tool for diagnosing MS. Most people with MS have abnormal MRI scans. MRIs of both the brain and spinal cord can help detect signs of MS.1
What is magnetic resonance imaging?
MRI is a medical imaging technique that uses magnets and radio waves to create pictures of the inside of your body. It is used to diagnose a variety of medical conditions. MRIs do not involve radiation like computed tomography (CT) or x-ray images. MRIs also reveal much more detailed pictures and more important information about the brain and spinal cord than CT scans.1,2
How does an MRI help diagnose MS?
The main use for an MRI in diagnosing MS is to show lesions in your brain and spinal cord. Lesions are areas of damage to the nervous system. An MRI is also helpful in detecting other changes in the brain and spinal cord that may be linked to MS.1
Types of MRI
There are many different types of MRI scans. To diagnose and manage MS, doctors will often order an MRI with intravenous (IV) contrast. IV means that the contrast is injected through a vein. This contrast helps your doctor see additional information about any lesions that are present.3
If you need IV contrast, the MRI technician will place an IV catheter into your arm. They will use it to inject the contrast or any other medicine you need during the MRI.4
Some types of MRI scans include:1,5
- T1 scans without contrast – This type of MRI scan shows the highest resolution images of the brain and spinal cord structure. However, research shows that scans without contrast may not be necessary to diagnose MS.
- T1 scans with contrast – This type of MRI scan shows newer, active lesions. Active lesions light up with contrast.
- T2/FLAIR images with contrast – T2/FLAIR images show both old and new inflammation in the brain. This type of scan shows the total amount of lesions from MS.
What are the possible side effects?
Most potential side effects of an MRI have to do with the contrast agent or with anxiety caused by the machine.3,4,6
Gadolinium-based contrast is the type of IV contrast used in MRI scans. Almost all people can tolerate this IV contrast without any symptoms or complications. However, MRI contrast can increase the risk of rare but serious kidney damage in people with severe kidney failure.6
Before having an MRI, talk to your doctor about any kidney problems and tell them what drugs you are taking. Include any over-the-counter medicines and supplements.6
In rare cases, the contrast agent might cause an adverse reaction such as:4
- Pain where the IV tube is inserted
Even more rarely, people are allergic to gadolinium-based contrast. Allergic symptoms might include:3
- Trouble breathing
- Feeling “tight” in your throat
- Rash or hives
Tell your doctor or nurse right away if you notice any of these symptoms. You might need medicine to help with the allergic symptoms and prevent an emergency.3
The MRI is a donut-shaped tube. Your head may be inside the tube, depending on the area that needs scanning. Some people feel anxious or claustrophobic during the MRI scan. If you feel anxious, talk to your doctor about taking something to calm your nerves.4,6
Other things to know
The MRI machine is a giant magnet. So, if you have any metal inside your body, you may not be able to have an MRI. This often includes people with:7
- Metal surgical clips
- Implanted metal plates or screws
- Cochlear implants
Some implantable devices may be MRI compatible. If you have a metal device in your body, talk to your doctor to find out if you can safely get an MRI scan.7
You will also need to remove any metal objects from your body before the test. This includes jewelry, watches, and clothing with metal zippers or snaps.4
The test itself is painless, but the machine is noisy. You will be positioned on a flat, moveable bed and given earplugs to protect your hearing.1,7
Keeping still is important during the MRI. You will hear a series of clicking and knocks, some loud. The bed you are lying on will move slightly depending on the image that needs to be taken. The technician will talk to you through a speaker during the test so you know what is going on.1,7