MRI scans

Andy Myles, Advanced MSK Physiotherapist

Understanding MRI scans, inside and out

31 January 2024

MRI stands for Magnetic Resonance Imaging. An MRI scan uses strong magnetic fields along with radio waves to create detailed images of the inside of the body. The scan can be used to examine almost any part of the body to:

  • help diagnose or monitor certain conditions
  • prepare for surgery or plan a course of treatment
  • assess how successful an operation has been.

It’s a completely non-invasive procedure and has become crucial in enabling doctors to make faster, more accurate diagnoses for a wide range of medical issues. Despite the important role MRI scans play in modern medicine, there are still some misconceptions surrounding the procedure.

We’ve put together this guide to provide details of what to expect if you need to have an MRI scan, as well as to debunk some common myths and ease any worries you may have.

What is an MRI scan used for?

An MRI scan is a completely non-invasive way of seeing what’s happening inside the body. It can be used to help find, identify and diagnose all kinds of conditions or issues within the body. Its primary uses include:

  • Examining and imaging soft tissue such as the heart and blood vessels, breasts, muscles and internal organs. It can detect and pinpoint anything from inflammation to tumours.
  • Neurological conditions from brain and spinal cord injuries to genetic abnormalities. An MRI scan can locate damage, identify brain activity or diagnose conditions like multiple sclerosis.
  • Musculoskeletal issues from diagnosing joint, ligament, bone or tendon injuries to assisting in identifying orthopaedic problems, MRI scans can be utilised to help analyse Injuries or conditions to evaluate treatment options – mainly the possibility of undertaking interventions such as surgery or injections.

What to expect from an MRI scan

When you get to the hospital, you’ll fill in a general health questionnaire and consent form. You’ll also need to confirm whether you have any metallic implants or fragments in your body as these could pose a safety risk and/or affect the quality of the imaging.

You may also be given an injection of a contrast agent (or dye) to help blood vessels and soft tissue show up more clearly. The hospital staff will discuss this with you on the day and ensure it’s safe before going ahead. This may be referred to as an MRA (Magnetic Resonance Arthrogram).

An MRI scanner is normally a large tube, open at both ends, with a mechanical bed that moves in and out of it. You’ll lie down on the bed and the staff will prep you for your scan. A frame may be placed over the area that’s being scanned to help get a more detailed image.

The scanner is operated by a radiographer who will sit outside the room at a computer, from where they’ll be able to monitor things and communicate with you. They’ll move the bed into the tube and you’ll need to lie there for the duration of the scan.


Can I eat and drink beforehand?

You’ll normally be able to eat and drink before your scan, though this depends on the area being scanned. In some cases, you may be given specific instructions about what to eat or drink.

What should I wear?

You may be given a gown to wear depending on what you’re having scanned. If not, loose fitting, comfortable clothing is fine. The most important thing is to ensure there are no metal zips, buttons or adornments on your clothes. If you’re unsure about your clothing, ask for a gown.

Is it uncomfortable?

You’ll need to lie as still as possible in a relatively confined space, so it might not be the most comfortable environment. You may have supporting pillows positioned around you to help keep you still and comfortable and you’ll be given ear plugs and / or headphones to help reduce the noise.

It can also get quite warm. Some people don’t enjoy it while others drift off to sleep. If you’re particularly worried about claustrophobia, you can ask for a sedative or even ask about the availability of open or upright MRI scanners.

Is it loud?

Yes. The MRI machine contains powerful magnets, which will make a loud tapping or clunking sound during the scan. This is the electrical current passing through the machine. It can feel quite loud from within the machine, which is why you’ll have the ear plugs and / or headphones.

Can I have someone with me?

If you’d feel more comfortable with someone there to keep you company, you can ask to have a friend or family member with you in the room. They’ll also need to remove any metallic objects and leave their phone and watch in a locker.

How long does it take?

The length of time you’ll spend in the scanner depends on what you’re having scanned. A larger area will take longer than a smaller body part, so an MRI scan can take anything from 15 to 90 minutes. If you’re given headphones to wear, you may be able to request music to help pass the time.

Common misconceptions

As with many other medical tests and procedures, MRI scans can be a bit daunting if you’ve never had one before. There are a number of common myths and misconceptions surrounding them, which don’t help if you’re feeling a little uneasy about it, so let’s bust some of the most common ones right now:

MRI scans expose you to harmful radiation – MRI scans involve magnetic fields along with radio waves, neither of which contain any radiation. So, while CT scans and X-Rays do expose patients to some ionising radiation, MRI scans don’t, which makes them one of the safest scans available.

MRI scans are painful – Uncomfortable, maybe. But they shouldn’t be painful. Of course, everyone is different and, if the reason for your scan is a particularly painful injury or condition, lying still for a long time might become painful, but the scan itself is completely non-invasive and you won’t feel the radio waves or magnetic fields at all.

MRI machines are all the same – There are actually a number of different types of MRI machines. They vary in terms of design, size and strength. As technology progresses, new types of MRI machines are developed to suit specific purposes or produce a better scan for certain body parts.

MRI contrasting agents are bad for you – Firstly, most MRA scans are conducted without using a contrasting agent or dye. But if it’s needed, the dye used in MRI scans is non-toxic and easily flushed from the body.

It can cause some short-term side effects such as dizziness or nausea, and in some rare cases, people may experience an allergic reaction. If you’ve had severe kidney issues in the past, you may have a blood test to determine whether or not it’s safe to use a contrasting agent.

MRI scans are only for serious conditions – MRI scans can be used to find, diagnose or rule out all kinds of issues. Anything from torn cartilage to a brain tumour.

People with metal implants can’t get MRI scans – This is probably the most common misconception, but also the least clear-cut. While it’s true that some metallic implants may prevent you from having an MRI scan, having metalwork in your body doesn’t automatically mean you can’t have the scan.

Technicians and doctors will assess it on a case-by-case basis, so make sure you inform them about any metal implant or other medical device you have prior to the exam.

While some metal objects, like pacemakers, can be affected by the MRI machine’s magnetic field, things like titanium implants, tooth fillings and cochlear implants are often compatible with MRI scanners.

Either way, technicians may need to take precautions to ensure your safety, so you should always inform them of any metalwork or medical device beforehand.

Further reading

NHS – MRI scan overview