Quick answer
What is an MRI scan?
An MRI scan is a type of imaging test that uses magnets and radio waves, not radiation, to produce detailed images of the brain, spine, joints and soft tissues. The scanner is tunnel-like and makes loud knocking noises, so ear protection is provided. Tell staff about any implants, claustrophobia or pregnancy beforehand.
How an MRI scan works
An MRI scan uses strong magnetic fields to align the hydrogen atoms in your body. Different types of tissue produce different signals in response, which the scanner converts into detailed cross-sectional images. This is what allows an MRI scan to show soft tissues, such as the brain, spinal cord and ligaments, in detail.
Safety screening before an MRI scan
Before your MRI scan, you will be asked to complete a questionnaire covering any metal implants, the possibility of pregnancy, and your kidney function if contrast dye is planned. This helps staff check that the scan will be safe for you. Any loose metal objects, such as jewellery, watches and some clothing, will need to be removed before you go into the scanning room.
What happens during an MRI scan
You will need to lie as still as possible during the scan, since movement can blur the images and mean parts of the scan need to be repeated. You can usually communicate with the radiographer throughout the scan, often through an intercom, so you can let them know if you feel unwell or uncomfortable.
Getting the results of an MRI scan
The images from your MRI scan are reviewed and a report is sent to the doctor who referred you, and results are usually discussed at a follow-up appointment. If the scan shows something that needs urgent attention, this is normally communicated to your referring doctor on the same day.
Common questions about the MRI scan
- Is an MRI scan safe if you have a pacemaker?
- Many modern pacemakers and other implanted devices are described as MRI-conditional, meaning they can be safe under certain scanning conditions. You should always tell staff about any implants you have before the scan so they can check whether it is safe to go ahead.
- What can you do if you are claustrophobic during an MRI scan?
- Options include using an open MRI scanner, arranging sedation, or using coping techniques to manage claustrophobia during the scan. It is best to discuss any concerns about claustrophobia with staff before your appointment so they can plan accordingly.
- Why is an MRI scanner so loud?
- The knocking and buzzing noises are a normal part of how an MRI scanner works and do not mean anything is wrong. Earplugs or headphones are provided to protect your hearing and make the scan more comfortable.
- What is the difference between an MRI scan and a CT scan?
- An MRI scan tends to give clearer images of the brain, spine and ligaments, while a CT scan is often quicker and more commonly used in emergencies. The choice between them depends on what part of the body needs to be examined and how urgently.