Having an MRI Scan: What Published Guidance Supports
The magnet is always on, which makes what you bring into the room a safety matter rather than a formality.
Key takeaways
- How long it takes: roughly fifteen to ninety minutes, depending on the area scanned
- Metal: tell staff about any pacemaker, implant, surgical clip or metal fragment in the eye
- Most useful single change: Tell the department about implants when you book, not when you arrive.
- Commonest mistake: Taking jewellery, watches, hearing aids or cards with magnetic strips into the scan room.
- See a doctor if any of the signs under "When to speak to a doctor" below apply to you.
What it is
A scan that uses a strong magnetic field and radio waves to image soft tissue, with no X-rays involved. It sits within Using Health Services. What follows are the published numbers, not the ones that get passed around.
The numbers, in one place
| Measure | Figure |
|---|---|
| How long it takes | roughly fifteen to ninety minutes, depending on the area scanned |
| Metal | tell staff about any pacemaker, implant, surgical clip or metal fragment in the eye |
| Noise | loud knocking throughout; ear protection is provided |
| Contrast | some scans use a gadolinium injection into a vein |
| Radiation | none |
What helps
The advice below comes straight from the guidance cited at the foot of this page.
- Tell the department about implants when you book, not when you arrive
- Say beforehand if you struggle in enclosed spaces, so sedation or an open scanner can be discussed
- Wear clothing with no metal fastenings, or expect to change into a gown
- Ask how and when you will get the results before you leave
What to avoid
The common mistakes, including the ones that sound sensible.
- Taking jewellery, watches, hearing aids or cards with magnetic strips into the scan room
- Assuming an old implant is safe because a previous scan went ahead
- Skipping the safety questionnaire because you have had a scan before
Where to go next
- What People Get Wrong About Having an MRI Scan
- Having an MRI Scan for Beginners: Where to Start
- Having an MRI Scan — the reference entry
- Having a Blood Test: Sorting the Evidence From the Noise
- The Evidence on NHS Referrals and Waiting Times, Without the Hype
When to speak to a doctor
Tell the radiographer before the scan if you have a pacemaker or implanted defibrillator, a cochlear implant, an aneurysm clip, or any history of metal fragments in your eyes. Tell them if you are or might be pregnant, and if you have kidney problems and contrast is planned.
Where this comes from
How this page was put together
Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarised or generalised beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.
Medical disclaimer
This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to a GP, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 999.
Spotted something wrong? Report an error on this page. We correct on the page and say what changed.
