Magnetic resonance imaging (MRI) and MS

MRI scans are un-invasive (no medical object goes into your body) and painless, although some people can find them claustrophobic. 

An MRI scan is used to create a detailed image of inside your brain or spinal cord. They’re very accurate and can pinpoint inflammation, damage or scarring. MRI scans confirm a diagnosis in over 90% of people with MS. 

What happens during an MRI scan

Before your MRI scan

When your doctor refers you for an MRI, tell them if:

• you have metal in or on your body
• you’re pregnant or breastfeeding
• you’re allergic to contrast agent (a substance you take that makes things on your scans show up more clearly)
• you have kidney problems.

You normally won’t have to fast (not eat or drink) before your MRI scan unless they tell you to.

Before your scan, you’ll need to remove all metal items like jewellery and any clothes with metal zips and fastenings. 

During your MRI scan

MRI scans are painless but some people can find them claustrophobic and the machine can be noisy. There’ll be medical staff with you to keep you as comfortable as possible.

During an MRI scan you’ll be asked to lie flat on a bed that’s then moved inside the scanner. The scan usually lasts for 15 to 90 minutes. You’ll be asked to keep as still as possible, so it’s important to get comfortable at the start.

Read Nicola's tips on having an MRI scan

After your MRI scan

An MRI scan is normally what we call an ‘outpatient procedure’. This means it’s something you have, then you go home the same day. If you’ve had a sedative, someone will need to take you home.

It might take a few weeks for your results to come back to your doctor or neurologist. 

The McDonald criteria are used to decide on an MS diagnosis and will include the results of your MRI. 

How does an MRI scan work?

An MRI scan uses powerful magnets and radio waves to take images of your brain or spinal cord.

MRI measures how much water there is in the body. Because different parts of the brain have different amounts of water, we can use MRI to distinguish them and build up pictures of the central nervous system, your brain and spinal cord.

The protective myelin coating is a fatty substance, so it repels water. This means we can measure how much myelin is present because it looks different to nerves and other cells in the brain or spinal cord on a scan.

Are MRI scans safe?

MRI scans are one of the safest medical procedures available, but may not be suitable for everyone. If you have a metal implant, such as a pacemaker or artificial joint, you might not be able to have an MRI scan. If you’re pregnant, you should speak to your doctor about whether an MRI scan is suitable for you.