About a brain MRI scan
An MRI scan of the brain uses a strong magnetic field, radio waves and a computer to make detailed pictures of the brain and the structures inside the head. It does not use X-rays or any other radiation, and it shows the brain in more detail than other imaging tests, including CT.
A brain MRI is used to investigate both sudden and long-standing symptoms, such as persistent or unusual headaches, dizziness or balance problems, changes in memory or thinking, seizures, numbness or weakness, and problems with vision or hearing. It is also used to monitor known conditions such as multiple sclerosis or a brain tumour. Your images are reviewed by a consultant radiologist, who writes a report for your doctor.
What happens during the scan
You lie on your back on the scanner bed with your head in a head coil, which fits around your head like a cage and has a mirror so you can see out. The bed then slides into the scanner. The scanner is loud, so you will wear ear plugs or headphones, and the radiographer can see, hear and talk to you throughout. It is important to keep your head very still. Some brain scans include an injection of contrast dye (gadolinium) into a vein in your arm to show certain conditions more clearly; where contrast is needed, it is charged separately.
If you feel anxious in enclosed spaces, let us know when you book. Some of our partner centres have wide-bore or open scanners, which can feel less enclosed.
What the scan can show
A brain MRI can help to look at:
- causes of headaches, dizziness and balance problems
- stroke and the effects of a previous stroke
- brain tumours and other growths
- multiple sclerosis and other conditions affecting the brain’s white matter
- causes of seizures and epilepsy
- age-related changes, such as loss of brain volume, and changes linked with memory problems
- bleeding or damage after a head injury
- infection and inflammation
- hydrocephalus (enlarged fluid spaces in the brain)
- problems with the pituitary gland, inner ear and the nerves to the eyes
Emergency symptoms: a sudden, extremely severe headache, drooping of one side of the face, weakness in an arm or one side of the body, slurred speech or sudden loss of vision can be signs of a stroke or bleed. Call 999 straight away. Do not wait for a scan.
Preparing for your scan
No special preparation is needed for most brain MRI scans, and you can eat and drink normally. Avoid wearing make-up, as some contains metallic particles, and remove hair clips and hairpins. If you have had a previous brain scan, upload the report when you book so it can be compared.
You can usually eat, drink and take your normal medicines unless the scanning centre tells you otherwise. Wear loose, comfortable clothing without metal zips or buttons, and leave jewellery at home. You will be asked to remove metal items such as hair clips, hearing aids, coins and keys, and you may be asked to change into a gown.
Before the scan you will complete a safety questionnaire. Tell the team if you have a pacemaker, any metal implant, surgical clips or other device, if you have kidney problems or allergies, or if you are, or might be, pregnant or breastfeeding. If you feel anxious in enclosed spaces, let us know when you book. Some centres can offer a relaxant, and if you take one you will need someone to take you home and must not drive for 24 hours.
Frequently asked questions
Is an MRI or a CT scan better for the brain?
MRI shows the brain in more detail than CT and does not use radiation, so it is usually preferred for investigating long-standing symptoms. CT is quicker and is often used in emergencies, such as suspected bleeding after a head injury.
Can a brain MRI find the cause of my headaches?
A brain MRI can show or rule out structural causes of headaches, such as a tumour or other abnormality. Most headaches, including migraine, do not show up on a scan, so a normal result is common and can be reassuring.
Will I need a contrast injection?
Not always. It depends on what your doctor is looking for. Contrast helps show some conditions, such as certain tumours, inflammation or infection. If contrast is needed, it is charged separately.
I am claustrophobic. Can I still have a brain MRI?
Most people manage with support from the radiographer. Let us know when you book. Some centres have wide-bore or open scanners, and some can offer a relaxant, in which case you will need someone to take you home.
Do I need a referral?
You can tell us if you have a referral from your GP, physiotherapist or consultant and upload it when you book. If you do not have one, select “no referral” when you book and the scanning centre will confirm the next steps with you.
Sources
The information on this page has been gathered from various sources and is provided for general information only. It is not medical advice. TOP MRI is not liable for the accuracy or completeness of this information. Please speak to your doctor or the scanning centre about your own situation.