MRI scans of the brain

MRI scans can diagnose aneurysms, clots, bleeding, stroke and many other problems in your brain, as Professor Joanna Wardlaw tells Senior Cardiac Nurse Emily McGrath.

An MRI scan taking place with a doctor reviewing the output on a computer screen 

1. Why would I have an MRI scan of my brain?

You may have an MRI scan to look for the cause of headaches, investigate tumours, help diagnose stroke or blood vessel problems in the head, and check for signs of brain diseases like multiple sclerosis and causes of dementia.

2. What will a brain MRI tell my doctor?

It’s very good at showing structural changes of the brain, muscles, ligaments and internal organs. It is better than CT scans for showing some details of soft tissue, including some abnormalities in the brain (CT is better for bones). MRI is helpful in diagnosing subtle early changes that indicate a higher risk of stroke and future cognitive problems (such as dementia).

3. What does an MRI scan involve?

It uses a magnetic field and pulses like radio waves to take pictures inside the body. You must make sure you don’t have any metal on you and sometimes you will be asked to change into a gown. You go into the scanner, which is like a large tube with a hole through it. You will be given ear plugs because it’s very noisy and some places play music while you are inside.

4. How long will an MRI scan of the brain take?

Usually a scan of your brain takes 20–30 minutes, but it depends what condition is being looked at.

5. Will having an MRI scan hurt?

No. About one in five people having this test may have an injection of magnetic dye called gadolinium, which is injected into a vein, but this shouldn’t be painful. The dyes used now are very safe and people very rarely have problems.

6. Is there anyone who shouldn’t have a brain MRI?

Before your appointment you will be asked if you have ever had any metal work in your body, including cochlear implants and intracranial aneurysm clips, as this could make MRI unsafe for you. The strong magnetic field means any iron-containing objects in or on your body would be moved with great force.

Newer pacemakers are usually MRI-compatible, but it’s important that you tell your doctor if you have a pacemaker or ICD so that they can check whether you can have the scan.

You will have to fill in a form to help assess whether it is safe for you to have it. It’s helpful if you wear clothing without metal parts. Tell your doctor if you are pregnant, although this won’t necessarily prevent you from having the scan.

7. Are there any risks of a MRI scan that I should be aware of?

Some people feel claustrophobic in the small space, but this is less common these days as the scanners have become more accommodating. People who have this concern may be able to visit the scanner beforehand to become familiar with it. Unlike CT scans, there’s no radiation involved.

8. What are the latest developments in brain MRI?

MRI is widely used in research into the brain and heart. Complex advanced methods can show blood flow, connections between different regions of the brain, activity in different parts of the brain during specific tasks like remembering words, chemical reactions in the brain or muscle, and heart function. In future, some of these methods may distil down to simpler methods for day-to-day use in hospitals.

Finding new treatments using brain MRI

The BHF is funding millions of pounds worth of research into preventing and treating stroke and vascular dementia, using MRI as a tool. For example, Professor Wardlaw is leading a research trial looking at potential new treatments for lacunar stroke, which is caused by damage to the tiny blood vessels deep within the brain. Her team will use MRI scans to see the effects of medications on these blood vessels.

At the John Radcliffe Hospital in Oxford, we’re funding Dr Luca Biasiolli to test a new MRI technique he has developed to detect which fatty plaques in the main artery supplying the brain are more likely to break off, causing a stroke. This new technique could help doctors treat patients earlier to prevent strokes.


Professor Joanna WardlawProfessor Joanna Wardlaw

  • Professor of Applied Neuroimaging, Head of Division of Neuroimaging Sciences and Director of the Brain Research Imaging Centre, University of Edinburgh
  • Honorary Consultant Neuroradiologist at NHS Lothian
  • Author of more than 400 publications
  • Recipient of University of Edinburgh Chancellor’s award for research and the British Society of Neuroradiologists President’s medal
  • Her groundbreaking studies have changed how patients with stroke are treated all over the world

Discover Professor Wardlaw's research into lacunar stroke and dementia.

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