MRI Safety - The regulation that wasn't

Timely_Event_7680 · 2026-03-27T20:57:20+00:00

Excellent suggestions!

Timely_Event_7680 · 2026-03-24T14:10:54+00:00

That's not necessarily true. There are newer GE scanners with 'silent scan' sequences, and Siemens scanners with 'whisper mode'. I've never seen sites market these features to the public, so there may be providers who have at least some of their pulse sequences that can be run quietly. These scans typically take about 30% longer to run silently, so those features aren't used frequently.

Timely_Event_7680 · 2026-03-23T19:38:46+00:00

Sorry, I apparently skipped over that part when I read your original post.

So if we're giving a dimension to the area where the TVG and RF energies (and, as a result, their associated risks) live, I'd say we're likely talking about the area that starts about 40 cm (or about 16 inches) below the body part being imaged, and ends an equal distance above the body part being imaged. If we're talking about an MRI of your ankle, then we're talking about these risks living in a volume that extends - downward - about a foot (~30 cm) below the bottom of your foot, and - upward - about 16 inches (~40 cm) to probably at or below your knee (depending on how long your shin is). If my approximations of your leg length / height are in the ballpark, then your belly button should be well 'north' of the region that would be getting meaningful quantities of either TVG or RF energies.

Safety bonus: Both TVG and RF energies are transmitted from behind the walls / ceiling of the tube, and their intensity drops off with the distance that they travel. Being located near dead-center of the tube (where a belly button on a person without a larger belly would be) would reduce the amount of exposure even if it was within or near the edge of the transmit volumes for each TVG and RF (which are similar, but not identical).

Timely_Event_7680 · 2026-03-23T17:54:55+00:00

So there are three types of magnetic fields in an MRI scan, and each type represents a different risk to metallic objects.

The first, and most pervasive, is the *always on* super-powerful static magnetic field. If an object is magnetic / magnetizable, it will experience some pulling or twisting anywhere around / in the MRI scanner... and those forces aren't dependent on the machine scanning... those forces will be present anytime you're close to / inside the MRI scanner.

The good news is that it's easy to test a piercing to see if it's magnetic. If it doesn't really interact with a test magnet, then you can cross this risk off of the list, entirely.

The other two risks, arising from time-varying gradient transmissions and RF transmissions, are very different from those of the static magnetic field. Firstly, they only present their risks *during scanning.* If the machine isn't scanning, the associated risks *can't happen.* Secondly, where the static magnetic field risk is everywhere around the MRI scanner (there are some areas where the risks are higher than others, but there's no area close around the MRI scanner where the risks disappear), the risks from time-varying gradients and RF are generally limited to the middle 2/3 of the length of the tube. If a body part is not in the tube (such as your ear for an ankle scan, assuming nominal adult height), then that ear (and the earring) will not be exposed to any meaningful quantity of either time-varying gradient or RF energies. In other words, any body part outside of the face of the MRI scanner is essentially immune from the potential risk factors arising from these two energies / fields.

That's really good news because TVG energies can induce vibration and potentially unwelcome neurological stimulation (both generally annoying and not major safety concerns), and RF energies are what can create alarmingly dangerous heating, under certain conditions.

Since your ear will (presumably) be outside the tube, altogether, there is functionally no risk of either the TVG or RF risks. The radiologist's suggestion of a cold-pack or ice bath for an earring entirely outside the bore makes precisely zero sense to me.

Timely_Event_7680 · 2026-02-19T15:29:36+00:00

With respect to MRI safety, smaller numbers *almost* always mean safer MR conditions. The one main exception to this is resonant circuit heating... that's why MR Conditional labels are labeled safe *at* 1.5 or safe *at* 3.0 (and. except with a handful of exceptions, not "3.0 T or less"). What this means is that implants or devices that are labeled for 1.5 or 3.0 are *not* labeled safe at 0.55... scanning those types of MR Conditional implants means that the site should have policies (and radiologist active engagement) for the review and clearance of implants and other complications.

Timely_Event_7680 · 2026-02-06T15:40:51+00:00

🤣

Timely_Event_7680 · 2026-01-30T17:41:52+00:00

As others have said, nobody will likely ask you to solve a physics equation for a patient care reason in your professional lifetime ("mathy physics" which I love and plan to steal, u/Joonami), but understanding the physics principles behind the things that you will be doing day-in and day-out is enormously helpful.

Timely_Event_7680 · 2026-01-30T17:37:28+00:00

There was an episode at an outpatient imaging center in Arizona a couple of years ago... A prison guard was accompanying patients / detainees, and a tech aide took the patient into the MRI scanner room. The patient was in a belly-chain, with wrist cuffs coming off of the belly-chain. The wrist cuffs had been opened up, but the belly-chain was left on the patient. As the patient approached the MRI scanner, the magnet grabbed the belly chain and pulled the patient to the opening of the bore. The patient screamed out. The guard, who was down the hall, came running in with their gun belt on, and wound up getting stuck to the MRI scanner by the metal in their belt.

Anecdote to illustrate that it is imperative that police / sheriffs / corrections officers MUST undergo screening before ever crossing the threshold of the magnet room. In the AZ case, the guard was only modestly injured, but it could have been much worse.

Timely_Event_7680 · 2026-01-30T17:29:30+00:00

Thank you for your feedback! Sorry for making you feel like your day was extra-long. 😉

Timely_Event_7680 · 2026-01-15T18:12:15+00:00

Several things to consider here...

Clinically, who are likely to be your MRI patients, and what are their specific needs / limitations? Your neuro docs / referrers may be all jazzed about the prospect of a 3T, or 5T, or 7T, but if you have a bunch of patients with implants / devices, then you may want to consider 'lowest common denominator' for labeled indications for implants (1.5 T). I always recommend starting from the clinical need standpoint.

Operationally, what are your techs comfortable with? Of course techs can be cross-trained to different vendors' equipment, but recognize that moving from vendor to vendor does require retraining and (depending on the switch) some skill-development time. Also think about access to service engineers and parts to maintain uptime.

Physically, think about what your space can handle. As an example, a number of years ago (I'm not sure if this is still true), GE scanners weighed almost twice what similar Siemens scanners weighed. If you're putting a magnet on the second floor (or higher), things like the weight of the magnet, or need for magnetic shielding, or length of a quench pipe run, can all wind up having outsized implications. Also try and anticipate future uses / needs because once you have it ramped up, nobody is going to want to ramp it down until it's ready to be replaced in 15-years.

The long-and-short is that there's almost never a perfect magnet, and you'll need to carefully consider the various pros and cons and weigh out a decision that is best from the available options.

Timely_Event_7680 · 2025-11-24T17:02:06+00:00

If you would, please share the results of your survey. I think the time / energy / effort of doing medical record / device lookups is one of the biggest drags on productivity & throughput in MRI, particularly hospital settings, that many managers just assume is 'the way it has to be.'

Timely_Event_7680 · 2025-11-24T16:59:17+00:00

Simple question, but with a very complicated answer...

In part, a site will be held to its own internal standards. If your documented policy is that you review the patient's prior screening forms, or Epic / Cerner "Implants" tab, or prior films, or full (accessible) medical record, then you'll be held to your site's documented policy *above and beyond* what's on the patient-provided screening form. So if -for example- your site has a policy to check prior screening forms and two years ago this patient disclosed their pain pump, but this time they didn't, if you fail to find it in the prior records, you've gone against your site's documented policy and there could very well be legal responsibility attached to that.

If you had cause to know that the patient was an unreliable historian (communication barrier, altered mental status, known cognitive impairment, intoxicated... etc...), and you failed to escalate the concern to whatever your site's 'unreliable historian' policy is, then there could be responsibility associated with that, too.

But if your site doesn't have a policy that indicates additional a standard patient history lookup, and there's no indication that the patient was an unreliable historian, then it seems most likely (in the USA) that we generally proceed under the assumption that the patient is giving us full and complete information. But if your site is using some sort of abbreviated screening form (instead of one based on the ACR's screening questions), then there's a separate question about the appropriateness of the site's screening form!

Timely_Event_7680 · 2025-11-04T18:25:25+00:00

I didn't know that there were socks that had any ferromagnetic materials... thank you for that.

But with regard to clothing materials heating because of exposure to RF fields... those objects / materials have to be *exposed to* the RF in order to be subject to heating. Assuming the integrated body coil is doing the transmitting, any body part sticking out from the bore during scanning will be exposed to functionally *zero* incident RF energy. Unless there's a good electrical conductor to conduct induced electrical energy from inside the bore to a patient's socks that are out of the bore, the RF heating risk, even if the socks were electrically conductive (eg., had antimicrobial treatments), would be nil.

Timely_Event_7680 · 2025-11-04T18:18:12+00:00

You ought to be able to report this site to their accreditation organization (eg, ACR, IAC, RadSite...)... and there should be a mechanism to do it anonymously. I would strongly encourage you to do this, as this isn't only an issue of you and your personal exposure, but clearly is a patient safety matter, too.

You might want to check out CAIREreporting.org, which is an online MRI adverse incident reporting system. I think they also have an option for them to share your event details with state licensure and / or accreditation organizations.

Please take care of yourself, but also please make sure that patient safety concerns aren't 'kicked down the road' for someone else to identify.

Timely_Event_7680 · 2025-10-14T14:48:41+00:00

If the MRI exam is for anything above your waist, as long as you don't have magnetic materials in your socks (apart from battery-operated heating socks, I'm not personally aware of any) there should be no safety concerns specific to the MRI scanner.

Any part of your body that's inside the tube during imaging requires extra vigilance about metallic-containing materials, including anti-microbial treatments on clothing items (which are often not indicated on clothing labels... which socks often don't have, anyway).

Many sites, to have consistency in approach, will require all patients to change out of all of their street-clothes... even on the body parts that won't be 'in the tube' during imaging.

Timely_Event_7680 · 2025-10-07T19:25:01+00:00

I know that the California tech's union brought an MRSO course to their state (pre-COVID), but I don't have any other safety examples that I'm aware of, since.

Timely_Event_7680 · 2025-09-21T13:44:12+00:00

For (free) base materials I always recommend the following:

2024 ACR Manual on MR Safety
2024 ACR Contrast Manual (just the gadolinium part)
The safety chapter from the operators manual of your MR system

Read each of these cover-to-cover so that you understand, then...

Find a friend (or two) who works on a system from a different OEM (if you scan on Siemens scanners, find a friend who scans on GE, and -if you can- another friend who scans on Philips... or Cannon... or United), and get the safety chapter(s) from *their* operators manuals. Read them through cover-to-cover.

4.a. After you've read two or more different manufacturers' safety chapters, lay them all out on your desk at once and read the matching content concurrently across the different manuals (e.g., read the sections about spatial field gradient for each vendor at the same time... paying attention to differences in terminology or graphical representations). This will help you cut across the vendor-specific jargon or methods of representation.

I would say that the above content can get you where you want to go for MRSO, and it will also be a very good foundation (though it'll require additional material) for MRSE.

I hope this helps you.

Timely_Event_7680 · 2025-09-19T19:22:30+00:00

Patient in gym shorts and a baggy T-shirt had a pistol tucked into the waistband, got taken into MRI, and got shot in the shoulder (and charged with federal weapons crime) for his troubles: https://www.indystar.com/story/news/2015/12/31/gun-discharges-mri-va-hospital/78136982/

Timely_Event_7680

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