In this lesson
- Why you are asked the same questions more than once
- What the questions about metal and implants are really for
- What to say about pregnancy, breastfeeding and kidneys
The magnet never switches off
The scanner is a very strong magnet, and it stays on all the time. That single fact explains almost every question you will be asked.
A strong magnet pulls on iron and steel. It can warm some metals, or interfere with electronic devices such as a pacemaker. So before anyone goes near the scan room, the team needs a clear picture of what is in your body, on your body, and in your pockets.
This is called screening. It is a safety check, not a quiz, and getting it right is the most useful thing you can do to help your scan go smoothly.
Why you are asked twice — or three times
You may fill in a form when you book, answer the same questions on the phone, then be asked again on the day. That repetition is deliberate, for the same reason an operating team checks your name more than once. People forget things, and answers change between booking and arriving. Nobody is doubting you.
Metal and implants
Your team will ask whether you have anything metal or electronic inside you. It helps to think back through your whole medical history, including things you may not think of as “implants”:
- A pacemaker, defibrillator or other heart device
- Cochlear implants or hearing devices
- Aneurysm clips, coils or stents
- Joint replacements, plates, screws, rods or wires
- A spinal stimulator, nerve stimulator or drug pump
- Contraceptive coils
- Metal fragments in your eye from grinding, welding or an old injury
- Tattoos, permanent make-up, or piercings you cannot remove
Having an implant does not automatically mean you cannot be scanned. Many modern implants are designed and tested for use in an MRI scanner, though usually only under particular conditions — a certain strength of magnet, or certain scanner settings. That is why the team needs to know exactly which device you have, rather than simply that you have one. If you have a card, a booklet or a letter about your device, bring it — the make and model matters far more than the name of the operation.
If you are not sure whether something is still inside you, say so. “I think I had a clip put in years ago, but I am not certain” is a genuinely helpful answer.
What to leave at home
You will be asked to remove metal from your body and clothing: jewellery, watches, hairpins, glasses, hearing aids, coins, keys, cards and phones. Many departments ask you to change into a gown. It is simplest to arrive in comfortable clothes without zips, studs or underwiring, and to leave valuables at home.
Pregnancy, breastfeeding and kidneys
Pregnancy. Everyone who could be pregnant is asked about it. Please do not feel awkward — it is a routine question asked of everyone, not a judgement. MRI does not use radiation, but your team will still weigh up whether the scan is best done now or later, and whether contrast is needed.
Breastfeeding. Tell the team. They will give you clear advice, especially if contrast is planned.
Kidneys. If your scan may need a contrast injection, you will be asked about kidney problems, diabetes, or any past reaction to contrast. This is because contrast leaves the body through the kidneys. Your team will ask, and may arrange a simple blood test first. Lesson 5 explains contrast in full.
What people often ask
I have a metal plate in my ankle. Will I be turned away?
Almost certainly not. Orthopaedic metal is very common and usually fine. Your team just needs the details so they can check.
Do I need to fast or stop my medicines?
For most MRI scans, no. Some scans of the tummy do ask you not to eat for a few hours. Your team will tell you exactly what applies to your scan.
What if I remember something on the day?
Say it straight away, even if you are already gowned and waiting. Late information is welcome, never a nuisance.
One thing to remember
The screening questions exist so the magnet is never a surprise. Answer them fully, bring any implant card, and say “I’m not sure” whenever that is the honest answer.
This is general information, not medical advice — your own imaging team knows your situation.
References
- RadiologyInfo.org (RSNA/ACR). How to Prepare for Your MRI Exam https://www.radiologyinfo.org/en/info/how-to-prepare-for-mri-exam
- RadiologyInfo.org (RSNA/ACR). MRI Safety https://www.radiologyinfo.org/en/info/safety-mr
- NHS. MRI scan https://www.nhs.uk/tests-and-treatments/mri-scan/