Magnetic resonance imaging (MRI) is very safe and most people can have the procedure, including pregnant women and babies.
However, there are some instances where an MRI scan may not be recommended because the strong magnets used during the scan can affect any metal implants or fragments in your body.
Before having an MRI scan, you should tell medical staff if you think you have any metal in your body, such as:
- a pacemaker – an electrical device used to control an irregular heartbeat
- an implantable cardioverter-defibrillator (ICD) – a similar device to a pacemaker that uses electrical shocks to regulate heartbeats
- a nerve stimulator – an electrical implant used to treat long-term nerve pain
- a cochlear implant – a device similar to a hearing aid that is surgically implanted inside the ear
- a drug pump implant – used to treat long-term pain by delivering painkilling medication directly to an area of the body, such as the lower back
- brain aneurysm clips – small metal clips used to seal blood vessels in the brain that would otherwise be at risk of rupturing (bursting)
- metallic fragments in or near your eyes or blood vessels (common in people who do welding or metalwork for a living)
- prosthetic (artificial) metal heart valves
- penile implants – used to treat erectile dysfunction (impotence)
- eye implants – such as small metal clips used to hold the retina in place
- an intrauterine device (IUD) – a contraceptive device made of plastic and copper that fits inside the womb
- artificial joints – such as those used for a hip replacement or knee replacement
- dental fillings and bridges
- tubal ligation clips – used in female sterilisation (an operation that permanently prevents a woman being able to get pregnant)
- surgical clips or staples – used to close wounds after an operation
Having something metallic in your body does not necessarily mean you cannot have an MRI scan, but it is important for medical staff carrying out the scan to be aware of it. This is so they can decide on a case by case basis if there are any risks, or if further measures need to be taken to ensure the scan is as safe as possible.
For example, you may be able to have an MRI with a pacemaker or defibrillator if a cardiologist (heart specialist) or another trained healthcare professional is able to make the device MRI-safe. They will also need to carefully monitor your heart rhythm during the procedure.
If you're unsure about whether or not you have metal fragments in your body, you will need an X-ray to confirm whether this is the case.
Some tattoo ink contains traces of metal, but most tattoos are safe in an MRI scanner. Tell the radiographer immediately if you feel any discomfort or heat in your tattoo during the scan.
There is no evidence to suggest MRI scans pose a risk during pregnancy. However, as a precaution MRI scans are not usually recommended during pregnancy, particularly in the first three months.