What happens if you bring metal into an MRI room?
A small ferrous object can turn into a deadly projectile in seconds, but even nonferrous metals (those not attracted to the magnetic field) can be cause for serious concern. And it might not be the reason you would expect.
An MRI machine is made of an incredibly powerful superconductive magnet. In fact, they use magnetic fields that are over 60,000 times stronger than Earth’s. That’s why bringing metal near them isn’t just risky — it’s potentially deadly.
Even something as small as a paperclip can get violently sucked into the scanner at high speed, turning into a dangerous missile. And if that ferrous metal is inside your body — like a pacemaker, metal implant, surgical screw, or foreign object— the risks can be catastrophic. Here’s why.
Metallic objects can move or shift in the presence of the MRI’s magnetic field and could injure anyone or anything caught in the way.
This is why before entering the MRI room, patients must remove all metal objects. Additionally patients and staff must ensure that there are no unsafe implants present. If they don’t the results could be life-threatening.
However, MRI accidents involving projectile events only account for about 9% of all reported MRI safety incidents. So what makes metal such a frequent safety issue? The bigger risk isn’t always what people think.
Metals like titanium, indium, or aluminum have seemingly no effect in the presence of the MRI magnetic field. So why is ALL METAL absolutely prohibited inside the MRI scan room?
Reason #1 General Policy vs Individual Cases
It is important to recognize that general policy, by its nature, presents a broad safety framework meant to account for all patient demographic. When it comes to medical devices, the stakes are particularly high, therefore all metal containing devices must be screened by staff and vetted by the manufacturer before allowing patients to enter the MRI zone 4 scan room.
One interesting case I remember is a patient with an implantable device arrived for their MRI. The patient had not notified the imaging center of the medical device prior to the appointment and the staff held off on the scan until they could confirm clearance from the manufacturer. The patient was adamant that they just had an MRI a few weeks ago and everything was cleared okay.
After a long back and forth; with the patient wanting to get her scan done, and the staff reluctant to go on just her word, it was decided to reschedule the appointment and wait until they could receive a response from the medical device manufacturer.
That decision may have saved the patient’s life because it turns out she did not have an MRI at all, she had a CT scan. The implanted medical device was not MRI safe, or even MR conditional. If the staff had relied on the patients word alone, then both the patient and the staff could have been put at serious risk.
Metals can heat up to 160 degrees Fahrenheit during an MRI scan.
This happens because metal can absorb the RF (radiofrequency) energy that produced by the MRI scanner causing them to heat up and possibly lead to patient burns.
In fact, thermal events account for about 59% of all reported MRI safety incidents.
Even nonmagnetic metals, like gold, silver, aluminum, and copper, have high electrical conductivity. These nonferrous metal can heat up significantly under RF exposure.
Everything from needles, electrodes, to implantable medical devices require the use of metals that do not react in the presence of the magnetic field, so they’re safe, right? Well not necessarily. Non magnetic metals, like Gold, Silver, Aluminum, and Copper have very high electrical conductivity and can heat up significantly under RF exposure.
Certain metals, like medical-grade titanium, niobium, zirconium, tantalum, and some stainless steel variants are generally considered safe in an MRI environment. These metals are nonmagnetic and have low electrical conductivity. However, all devices must be cleared before entering the MRI Zone 4 boundary.
When metal heats up in an MRI, it doesn’t happen instantly. A common analogy is a fork in the microwave, but a better one might be a frog slowly heating in warming water. The rise in temperature is gradual and may not be immediately obvious.
Patients may not notice heating until it’s too late, so it’s critical to report any unusual sensations during a scan. MRI patients are given an emergency squeeze bulb for this reason.
Sedated patients, especially inpatients, face the greatest risk since they may not recognize or report heating sensations. This is one reason why sedation should be avoided during MRI scans whenever possible.
The real reason metal is never allowed in an MRI room comes down to safety. Projectile events burns, the risks are too great to take chances. Even “safe” metals must be carefully evaluated and cleared before entering Zone 4.
If you’d like to learn more about MRI safety, check out the resources linked below. Hopefully this article has given you a clearer picture of why bringing any metal into an MRI room is never worth the risk.
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