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Patient Guides6 min read15 June 2026

MRI Safety Guide: Pacemakers, Implants, and Claustrophobia

MRI is incredibly safe because it uses no radiation. However, the powerful magnetic field means strict safety checks are required for patients with implants or pacemakers.

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Dr Sarah Okonkwo
Consultant Radiologist

Magnetic Resonance Imaging (MRI) is one of the safest medical imaging techniques available because it does not use ionising radiation (unlike X-rays or CT scans). However, because MRI machines use extremely powerful magnets, they pose unique safety challenges. Before any MRI scan, you will complete a detailed safety questionnaire to ensure you can be scanned safely.

Why is metal a problem in an MRI?

The MRI scanner's magnetic field is always on and is strong enough to pull heavy metallic objects across the room. More importantly for patients, the magnet can pull on ferromagnetic (iron-containing) implants inside the body, and the radio waves used during the scan can cause certain metallic implants to heat up.

Common implants that require special checks:

  • Cardiac pacemakers and implantable defibrillators (ICDs)
  • Cochlear (ear) implants
  • Aneurysm clips in the brain
  • Neurostimulators
  • Programmable hydrocephalus shunts
  • Some artificial heart valves
If you have a pacemaker or an aneurysm clip, you MUST inform the booking team immediately. Many modern pacemakers are "MRI-conditional", but they require specialist cardiac support during the scan, which is not available at all private centres.

What about joint replacements and dental work?

Most orthopaedic implants (such as hip or knee replacements, plates, pins, and screws) are made of titanium or non-magnetic stainless steel. These are completely safe in an MRI scanner. However, they can cause "artefacts" (distortions) on the images if they are very close to the area being scanned. Dental fillings, braces, and implants are also safe, though braces may distort brain or facial scans.

Managing claustrophobia

Around 10% of patients experience claustrophobia in an MRI scanner. The tube (bore) is well-lit and open at both ends, but it is a confined space. If you are anxious, tell the radiographer. They can provide eye masks, headphones with music, and a panic button so you are always in control. Some centres also offer "wide-bore" scanners which provide significantly more headroom.

Can I have an MRI if I am pregnant?
MRI is generally considered safe during pregnancy, but as a precaution, it is usually avoided during the first trimester unless absolutely clinically necessary.
Are tattoos safe in an MRI?
Most tattoos are completely safe. Occasionally, older tattoos or certain colours containing iron oxide may feel warm or cause a slight tingling during the scan. Tell the radiographer if you feel any discomfort.