What is an MRI Scan and How Does It Work?

If you’ve been referred for an MRI scan, you probably have questions. What exactly is it? How does it work? Will it hurt?

MRI scans might sound technical, but they’re actually one of the safest and most effective ways to see what’s happening inside your body. This guide will explain everything you need to know.

MRI stands for Magnetic Resonance Imaging. It’s a type of scan that uses powerful magnets and radio waves to create detailed pictures of the inside of your body.

Unlike X-rays or CT scans, an MRI doesn’t use any radiation. Instead, it works with the natural properties of water molecules in your body to build incredibly clear images of your organs, tissues, bones, and joints.

MRI scans are particularly good at showing soft tissues like ligaments, tendons, muscles, the brain, and internal organs. This makes them invaluable for diagnosing injuries, diseases, and conditions that other scans might miss.

The technology has been used safely in hospitals and clinics since the 1980s. Millions of MRI scans are performed every year across the UK.

The science is simpler than you might think.

Your body is around 60% water. Water molecules contain hydrogen atoms, and each hydrogen atom has a proton at its centre. These protons behave like tiny magnets.

When you lie inside the MRI scanner, a powerful magnetic field makes all these protons line up in the same direction, like compass needles pointing north.

The scanner then sends radio wave pulses through your body, knocking the protons out of alignment. When the radio waves stop, the protons snap back into position and release tiny radio signals.

Different tissues (bone, muscle, fat, organs) contain different amounts of water. This means their protons realign at different speeds and release different signals.

The scanner detects these signals and a computer processes them to create detailed cross-sectional images from multiple angles. The result is highly detailed pictures showing both the structure and condition of your internal tissues.

MRI scans can examine almost any part of your body and detect a wide range of conditions.

Common uses include:

They’re also used to monitor existing conditions and treatment progress. Because they don’t use radiation, they’re safe to repeat as needed.

One of the biggest advantages of MRI is safety.

Because MRI uses magnetic fields and radio waves rather than radiation, there are no known long-term health risks. You can have multiple scans without cumulative radiation exposure.

The magnetic field is harmless. You won’t feel it, and it doesn’t damage your cells or DNA.

However, powerful magnets affect certain metal objects, so you’ll remove all jewellery and metal items before your scan. Some medical implants like pacemakers or certain aneurysm clips may not be MRI-compatible, though many modern implants are now safe.

You’ll complete a safety questionnaire before your scan. If you have any metal in your body from surgery, let the team know so they can check compatibility.

MRI scans are usually avoided in early pregnancy unless essential. While there’s no evidence of harm, doctors prefer caution.

Some scans use contrast dye (usually gadolinium) to make tissues show more clearly. This is generally safe, though some people experience mild side effects like a metallic taste.

You might be wondering why you need an MRI rather than an X-ray or CT scan.

Each type of scan has different strengths.

X-rays are quick and excellent for looking at bones, making them ideal for diagnosing fractures.

CT scans are also fast and good for detecting bleeding, blood clots, or injuries from accidents. They use X-rays to create cross-sectional images.

MRI scans take longer but provide far more detailed images of soft tissues. They’re the best choice when doctors need to examine ligaments, tendons, muscles, the brain, spinal cord, or internal organs in detail. They’re also completely radiation-free, making them safer for repeated use and for younger patients.

The main downsides of MRI are that scans take longer (typically 15 to 60 minutes), the machine can feel enclosed which some people find uncomfortable, and the scanner makes loud knocking noises during the scan.

Your doctor will recommend the most appropriate scan based on what they need to investigate. In some cases, you might need more than one type of scan to get a complete picture.

Knowing what to expect helps you feel more relaxed.

At Vitalscan, we use the Philips 1.5T BlueSeal scanner, combining advanced imaging with comfort features like ambient lighting, entertainment options, and spacious design. Read more about your experience with us.

MRI scans are safe for children and performed regularly at our Milton Keynes clinic. Parents can usually stay in the room. For younger children, we can arrange positioning support or mild sedation to help them remain still and comfortable.

No. An MRI scan is completely painless. You won’t feel the magnetic field or radio waves. The only sensation might be a slight warmth in the area being scanned.

This is a common worry. Modern MRI scanners are much more open than older models. Our scanner has a 70cm bore and ambient lighting to reduce any closed-in feeling. You can also listen to music, watch videos, and use the buzzer if you need a break. For severe claustrophobia, speak to your GP about sedation options.

Yes, in most cases a friend or family member can stay in the room with you during the scan for support. They’ll need to complete their own safety questionnaire.

MRI images need to be carefully reviewed by a specialist radiologist. At Vitalscan, you’ll typically receive your results within 3 to 5 working days. Your GP or consultant will discuss the findings with you.

If you need an MRI scan, you don’t need to wait weeks or navigate complicated referrals.

At Vitalscan in Milton Keynes:

The process is straightforward and designed around your needs.

Browse our MRI scans or get in touch to discuss your requirements.

MRI scans are one of the safest and most powerful diagnostic tools available. They provide detailed images that help doctors diagnose conditions accurately and plan the right treatment for you.

While the technology might seem complex, the experience itself is straightforward and painless. Understanding what to expect can make the process much less daunting.

If you have any questions about MRI scans or would like to book an appointment at our Milton Keynes clinic, our team is here to help. We’re committed to making your experience as comfortable and reassuring as possible.