Computerised medical imaging is now a common diagnostic tool for a wide range of conditions. You’ve likely heard of MRI and CT scans, but how much do you really know about them?

To help you better understand MRI scanning technology, here are 25 fascinating and insightful MRI facts.

1. MRI Scans Don’t Use Radiation

A common misconception is that MRI scans expose patients to ionising radiation. In reality, they do not. This confusion often arises because MRI is mistakenly associated with Computed Tomography (CT) scans and Positron Emission Tomography (PET) scans, both of which use X-rays and carry a small radiation risk with repeated use. Since MRI scans rely on a different technology, they are safer for repeated imaging.

2. MRI Machines Use Powerful Magnets

Instead of radiation, MRI scanners use very strong magnets and radio waves to generate detailed images of the body. MRI stands for Magnetic Resonance Imaging. When the machine is activated, its strong magnetic field aligns the protons in the body’s hydrogen atoms. Radiofrequency pulses then disrupt these protons, and as they return to their original state, the energy they release is measured by a computer to create images.

Despite the magnetic properties of an MRI machine being up to 60,000 times stronger than the Earth’s magnetic field, these machines are completely safe for most patients. However, individuals with certain metal implants or medical devices may need alternative imaging methods.

3. You Don’t Need A GP Referral To Book A Scan

For NHS patients, a doctor’s referral is typically required to access an MRI scan. However, private providers often allow patients to book an MRI without a referral. Many private imaging centres accept self-referrals or referrals from other qualified medical professionals. If you self-refer, the facility should provide a clinician to oversee the process and refer you directly.

That said, if you have health insurance, your provider may require a doctor’s involvement to cover the cost, so it’s important to confirm their policies beforehand.

4. The First MRI Body Scan Was Performed Nearly 50 Years Ago

On 3rd July 1977, American physician and scientist Raymond Damadian performed the first MRI scan on a living human body. Using a scanner he developed, he produced cross-sectional images of his postgraduate assistant Larry Minkoff’s chest. A few years earlier, Damadian had discovered that hydrogen atoms in cancerous tissues emitted different signals than those in healthy tissues - an insight that paved the way for MRI technology in medical diagnostics.

5. However, the History of MRI Technology Can Be Traced Back Nearly A Century

In the 1930s, Austrian-born American physicist Isidor Isaac Rabi developed a method of measuring the magnetic properties of protons. He studied how atoms behave when exposed to radio frequency signals in a magnetic field, a principle known as nuclear magnetic resonance (NMR) - the foundation of MRI technology. Rabi was awarded the Nobel Prize in Physics in 1944 for this discovery.

6. You Can Use Private MRI Scans To Access NHS Care

If you have a private MRI scan in the UK, you can use the results to seek NHS treatment if a medical issue is detected. However, you will need to cover the cost of the private scan unless your GP refers you and no NHS scans are available.

Once you receive your scan results, take the report to your GP. While doctors are not required to accept private scan results for patients, they usually do if the scan has been conducted properly and overseen by a qualified clinician. If necessary, your GP will use the findings and refer you to an appropriate NHS specialist.

7. MRI Scans Offer the Clearest Imaging of Soft Internal Structures

MRI scans are not only very safe but also offer the highest level of detail for imaging of soft tissues compared to other scanning methods. The superior contrast makes it easier to detect tumours, lesions, and abnormalities that might be too small or unclear on CT scans or X-rays. This early detection can lead to the diagnosis of serious conditions before symptoms even appear. MRI is the preferred imaging method for examining most organs, blood vessels, veins, joints, spine and the spinal cord.

8. MRI Was Originally Called Nuclear Magnetic Resonance (NMR)

Nuclear Magnetic Resonance (NMR) was the standard term for advancements in the field following Dr Rabi’s work in the 1930s. This terminology remained in use until the late 1970s, when it shifted to Magnetic Resonance Imaging (MRI) after Dr Damadian’s first successful live body scan. The change was driven by concerns over the word “nuclear”, which carried negative connotations and public fears related to radiation. Additionally, the new term helped differentiate MRI technology from nuclear medicine, a separate medical speciality that uses radioactive tracers for diagnosis and treatment.

9. You Don’t Need to Prepare For an MRI Scan

Unlike some medical scans, a standard MRI typically requires little to no preparation. Simply arrive a few minutes before your appointment. You will likely need to complete some paperwork regarding your medical history and may receive a brief explanation of the procedure. After you have changed into a hospital gown, the radiographer will position you in the scanner.

10. However, You Will Need To Remove Metal Objects Before a Scan

Since MRI machines use strong magnets, all removable metal objects must be taken off to prevent interference with the strong magnetic field. These may include.

Jewellery (including piercings)
Hearing aids
Dentures
Hair clips
Wigs
Makeup containing metallic particles

If you have any permanent metal implants, inform the MRI facility in advance, as they may affect the scan or require an alternative imaging method. Examples include.

Pacemakers
Metal plates or screws
Aneurysm clips
Cochlear implants
Metallic dental implants

Some tattoo inks contain metallic pigments that may react during the scan. While this is uncommon, it could cause mild tingling or a slight burning sensation.

11. There Is Plenty of Support Available if You Feel Anxious or Uncomfortable Before a Scan

While an MRI scan is safe and non-invasive, it requires you to remain still inside a long tube for up to 90 minutes, depending on the scan type. If you experience claustrophobia, most facilities can provide a mild sedative to help you relax. Additional comfort measures may include headphones with soothing music, eye masks, cushions, and supportive pads. Some centres also offer wide-bore machines with a larger opening, or open scanners with open sides, to help reduce feelings of confinement.

MRI scanners are equipped with a two-way intercom, allowing you to communicate with the radiographer at any time if you feel anxious or need assistance.

12. MRI Scans Capture Images from Multiple Angles

MRI scans capture highly detailed images of tissues and organs from multiple angles, offering doctors a comprehensive view of the body's internal structures. By generating image slices across different planes - such as axial (horizontal), sagittal (side-to-side), and coronal (front-to-back) - MRI technology allows for thorough evaluation of bodily anatomy and function. These images can be compiled into near-real-time moving visuals, helping doctors assess dynamic processes like blood flow through the brain or veins.

13. MRI Machines Can Be as Loud as 120 db

One drawback of MRI scanners is the loud noise they produce. The strong magnets and electric currents generate a series of buzzing, drilling, clanging and tapping sounds that can reach volumes of 120dB - comparable to an ambulance siren or fireworks. While not inherently dangerous, this noise can be uncomfortable or even painful. To minimise the impact, scanning facilities provide a choice of earplugs and noise-cancelling headphones for patients.

14. There Are Different Types of MRI Machines

There are several different types of MRI machine, each designed for specific needs. The three most common types are.

Closed MRI machine - the standard scanner, featuring a long open-ended tube about 60cm wide.
Wide-bore MRI machine - a slightly larger version, typically 70cm in diameter, offering more space for larger patients or those with claustrophobia.
Open MRI machine - designed with an open-sided C-shape rather than a fully enclosed tube. While more comfortable, these scanners generally produce lower-quality images compared to closed models.

15. New High V MRI Machines Overcome Some of the Previous Limitations of the Technology

Traditional MRI scanners use a minimum magnetic field of 1.5T (approx. 30,000 times stronger than the Earth’s magnetic field), with some machines reaching 3T. However, recent technological advancements have introduced the 0.55T High V MRI machine, designed to address the limitations of standard scanners.

The primary benefit of High V MRI is reduced interference from metal implants, making it more suitable for patients with prosthetics or surgical hardware. Additionally, it offers better lung imaging, as the lower magnetic field minimises air-tissue distortion - a common issue in conventional MRI scans.

16. You May Soon Be Able to Get Scanned on a Portable MRI Machine

Until now, MRI scans have only been available at fixed locations such as hospitals and imaging centres. However, advancements in low-magnetic-field High V MRI have increased the feasibility of mobile MRI machines that can be transported in trucks. These portable units can be used in homes, schools, emergency situations, and remote or underserved areas with limited medical facilities. A pilot programme led by King’s College currently operates portable MRI machines in 20 countries across Asia and Africa.

17. MRI Scans Are Used For A Wide Range of Research Purposes

Because MRI scans do not involve radiation exposure, they are widely used in scientific research beyond medical applications. MRI technology has helped researchers study changes in both the mind and body, such as physiological effects during childbirth and emotional responses to music. It has even been applied in studies of animal brains, food properties, and historical artefacts.

18. Magnets Used in the Machines Need To Be Cooled to Absolute Zero

The superconducting magnets essential for MRI scanners generate heat during operation and must be cooled to near absolute zero (-273°C) to function properly. This is achieved using liquid helium, the coldest element on earth. A standard MRI machine contains around 2,000 litres of liquid helium and consumes approximately 10,000 litres over its lifetime.

19. MRI Scans Use A Safe Contrast Agent

Most MRI scans do not require a contrast agent, but in some cases, a gadolinium-based dye is injected to enhance image clarity. This dye is generally very safe, with only minor side effects such as dizziness, nausea, or mild rashes in rare cases. The risk of allergic reactions or side effects is lower than that of iodine-based agents commonly used in CT scans. However, in individuals with severe kidney disease, the contrast agent may cause damage to tissues, so its use is typically avoided in these cases.

20. Scans Can Study Thoughts and Emotions, But They Cannot Read Your Mind!

Functional MRI (fMRI) is used to map brain activity during cognitive and emotional tasks. By analysing changes in blood flow within the brain, researchers can identify which areas are active during different experiences. However, fMRI cannot directly “read” a person’s thoughts - it only provides insights into patterns of brain activity associated with certain tasks or emotions.

21. MRI Machines Can Cost Over £1 Million

State-of-the-art medical technology comes at a high price. The cost of a new MRI machine ranges from approximately £50,000 for a low-field (0.2T-0.5T) scanner to over £1 million for a high-field (3T) device - excluding delivery and installation costs. In many cases, scanners have to be lifted on a crane and delivered through the roof of a clinic!

22. You Can Get A Full Body MRI Scan For a Health Checkup

MRI scans aren’t just for diagnosing serious conditions - they also play a key role in preventative healthcare, even for individuals without symptoms. Full body MRI scans are increasingly popular among those seeking a comprehensive health assessment, such as individuals with a family history of certain diseases or athletes looking for peace of mind. A full body scan typically takes 60-90 minutes and costs around £1,500. While most people can undergo this scan, certain groups, such as pregnant women in their first trimester, are generally advised against it.

23. You Need To Stay As Still As Possible During a Scan

It is important to stay as still as you can for the duration of your scan. This is so as not to interfere with image clarity. MRI machines measure signals from your body’s hydrogen atoms, and movement can blur and distort these images. Staying still can be challenging, as scans take a bit of time and you will need to hold your breath for 10-20 seconds at a time. However, radiographers provide plenty of pause periods when you can relax, making the process easier.

24. MRI Scans Are Highly Effective At Detecting Serious Conditions

Thanks to their superior soft tissue imaging capabilities, MRI scans can be used for the diagnosis of a wide range of serious illnesses. According to the American Academy of Neurology, MRI scans are more effective than CT scans for detecting strokes. They can also help identify conditions in their early stages, including.

Cancer
Brain and spinal cord conditions, including dementia and Multiple Sclerosis (MS)
Vascular disease
Organ disease
Musculoskeletal conditions, including arthritis

25. You Can Get an MRI Scan For Your Pet

Here’s a fascinating final MRI fact. While you may know that MRI scans are safe enough to be routinely used on children, did you know that vets also use them to diagnose conditions in pets like dogs, cats, and rabbits? The scanning process is similar to that for humans, but animals are typically placed under anaesthesia to ensure they remain still. Because of this, pet owners are usually advised to withhold food for about 12 hours before the scan.

Get an MRI Scan

Need to check a health concern? You can book a private MRI scan yourself without a GP referral. The process is quick and simple, taking just a few minutes. Choose a convenient location near you, and one of our clinicians will contact you to explain what to expect. They will also provide follow-up support, advising on next steps and helping you access further treatment if necessary.

Sources

25 Interesting Facts About MRI Scans

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