Quick answer: in most cases, yes. Joint replacements, plates, screws and dental work are generally not a safety problem, and many newer pacemakers, defibrillators, cochlear implants and nerve stimulators can be scanned under specific conditions. A few devices, such as certain older pacemakers and some brain aneurysm clips, can make an MRI unsafe. The key is that the MRI team must know the exact make and model of any implant before you enter the scanner room. Tattoos are almost always fine, but tell the technologist if one feels warm.
The safety questionnaire is the part of my job I take most seriously. The MRI magnet is always on, and most problems are avoided simply by knowing in advance what is inside the patient’s body.
Why metal matters in an MRI
The MRI magnet can affect metal and electronic devices in three ways:
- Pulling and movement. Metals that are strongly attracted to magnets (ferromagnetic metals, such as iron) can be pulled with great force. An implant made of these metals could move inside the body.
- Heating. The radio waves used during the scan can heat some implants, wires and metal-containing materials, which can cause burns.
- Malfunction. The magnetic fields can disrupt electronic devices such as pacemakers, neurostimulators and pumps, or damage external devices such as hearing aids.
A fourth issue affects image quality rather than safety: metal near the area being scanned can create distortions, called artifacts, that make part of the image hard to read. The radiologist can often adjust the scan if they know the metal is there.
MR Safe, MR Conditional and MR Unsafe
In the U.S., medical devices are labeled with one of three terms, defined by the FDA and an industry standard (ASTM F2503):
| Label | What it means for you |
|---|---|
| MR Safe | Contains no metal or conductive material and poses no known MRI risk. |
| MR Conditional | Can be scanned safely, but only under specific conditions: for example, a certain magnet strength, settings or device mode. The MRI team must know the exact model to follow those conditions. |
| MR Unsafe | Poses unacceptable risks in the MRI environment. You should not have an MRI with this device in place. |
Most modern implants that contain metal are MR Conditional. That label is good news: it means the device has been tested and can be scanned when the instructions are followed.
Implant by implant
| Implant or item | Can you usually have an MRI? | What to do |
|---|---|---|
| Joint replacements (hip, knee, shoulder), plates, pins, screws, spinal rods | Yes, generally no safety risk | Mention them; they may distort images near the area |
| Dental fillings, crowns, braces, retainers | Yes, usually unaffected | Mention them; they can distort images of the face or brain |
| Pacemakers and implantable defibrillators (ICDs) | Often yes for newer MR Conditional models; some older devices cannot be scanned | Give the exact make and model well in advance; special procedures are needed |
| Cochlear implants | Depends on the model | Give the exact model; some are acceptable, some are not |
| Brain aneurysm clips | Depends on the clip | The exam is not done if the clip is ferromagnetic; the type must be confirmed |
| Neurostimulators, spinal cord stimulators | Depends on the model | Give the exact model; special settings may be required |
| Medication pumps (insulin, pain medication, chemotherapy), external or implanted | Depends on the device | Tell the team when booking; they will explain what to do with it |
| Vascular clips and catheters with metal parts | Must be checked | Mention any recent surgery or catheter |
| Bullets, shrapnel or metal fragments | Depends on location and material | Always mention them; fragments could move |
| Metal in or near the eye | Must be checked first | Mention any work with metal grinding or welding; an x-ray may be taken |
| External hearing aids | Removed before the scan | Bring the case |
| Body piercings | Removed before the scan | Remove them at home if you can |
| Tattoos and permanent eyeliner | Almost always yes | Tell the technologist if a tattoo feels warm |
If you are not sure what you have, you are not alone. Many patients do not know the model of their device. The next section explains how to find out.
From the scanner room: [TU EXPERIENCIA: un caso real (sin datos identificables) en que la tarjeta del dispositivo o una pregunta del cuestionario evitó un problema, o en que un paciente pensó que no podía hacerse la prueba y al final sí pudo.]
Pacemakers and defibrillators
For many years, a pacemaker meant no MRI. That has changed: many newer pacemakers and defibrillators are designed to be MR Conditional. Scanning them still requires preparation, because the device usually needs to be checked and set to a special mode before the scan and checked again afterward, and the scan must follow the device’s specific conditions.
If you have a pacemaker or defibrillator:
- Tell your doctor when the MRI is ordered, not on the day of the scan.
- Find your device card, which lists the manufacturer and model. The leads (wires) matter too.
- Expect the imaging center to coordinate with your cardiology team. Not every facility scans patients with these devices, so ask when you book.
Tattoos and permanent makeup
Tattoos rarely cause problems. Some inks, especially older or darker ones, contain metallic particles. In rare cases a tattoo can feel warm, tingle or become irritated during the scan, and very new tattoos can smear. Tattooed eyeliner can also distort images near the eyes.
Tell the technologist about large tattoos or permanent makeup near the area being scanned, and speak up immediately if any tattoo feels hot. The technologist may place a cool cloth on it or adjust the scan.
Clothing and cosmetics: the hidden metal
Some items that look harmless can heat up:
- athletic wear, socks and braces with metallic threads or metal-based antibacterial treatments
- makeup, nail polish or cosmetics with metallic particles, if applied near the area being scanned
- some hair products
This is why most centers ask you to change into a gown. See our [link: How to Prepare for an MRI] checklist.
How to find out what implant you have
- Look for your implant card. Many devices come with a wallet card listing the manufacturer, model and MRI status.
- Ask the surgeon or hospital that placed the implant for your operative report or device details.
- For cardiac devices, contact the cardiology clinic that follows your pacemaker or defibrillator.
- Send the information to the imaging center before the appointment. The scan cannot go ahead until the type of implant is confirmed and documented.
If there is any doubt about metal in your body, the center may take an x-ray before the MRI.
What if they say you cannot have an MRI?
Ask why, and ask about alternatives. Depending on the question your doctor needs answered, a CT scan or ultrasound may help. See [link: CT Scan vs MRI]. Some facilities have more experience with specific devices, so another MRI center may be able to scan you. You can search for accredited facilities in the ACR Accredited Facilities Database.
Tips from the technologist
[TU EXPERIENCIA: 3-4 consejos propios. Ideas: hacer una foto a la tarjeta del implante y llevarla en el móvil, no dar por hecho que «es de titanio, no pasa nada», avisar aunque la cirugía sea antigua.]
Frequently asked questions
Can I have an MRI with a hip or knee replacement?
Yes, in general. Joint replacements pose no safety risk in most cases. They can distort images close to the implant, so the radiologist may adjust the scan.
Can I have an MRI with a pacemaker?
Often yes, if it is a newer MR Conditional device and the scan follows its conditions. Some older pacemakers cannot be scanned. Your cardiology team and the imaging center must confirm the exact model first.
Can I have an MRI with tattoos?
Yes. Rarely, a tattoo can feel warm or irritated. Tell the technologist if you feel heat.
Do I need to remove my dental fillings or braces?
No. They are usually unaffected by the magnet, but they can distort images of the face or brain.
Is titanium safe in an MRI?
Titanium is not strongly attracted by the magnet, which is one reason many orthopedic implants are safe. But the safety of any implant depends on the whole device, not just one metal, so always give the team the exact details.
What should I do if I forgot to mention an implant?
Tell the technologist as soon as you remember, even if you are already in the room. It is never too late to stop and check.
For the rest of the process, see [link: What to Expect During an MRI].
This article is for general information and does not replace advice from your doctor or imaging team. Only the MRI team can confirm whether your specific device is safe to scan.