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Inside The Scanner Room? Too Little, Far Too Late!

Many facilities planning for ferromagnetic detectors, particularly existing MRI providers who must retrofit the new technology into tight-fit suite layouts, have a hard time finding optimal locations for the new MRI pre-screening instruments.

Real estate within the outer walls of the hospital is at such a premium that a good proportion of MRI providers are already working within MRI suites into which their large (and frequently growing) operational requirements have been shoehorned-in. They could really do with several hundred additional square feet, so the addition of anything to the suite can trigger a domino series of complications.

Pass-through ferromagnetic detection portals, such as the Mednovus Sentinel® series products, can be sited as either free-standing or doorway-mounted instruments. One caveat for doorway-mounted versions is that the door should not swing through the aperture of the portal (door hardware, even on most RF-shielded doors for MRI suites, has ferromagnetic components and would set off the detector). This means that there is one side of the doorway that is ill-suited to receive a mounted portal.

For MRI suites where space is already at a premium, it is sometimes felt that mounting a ferromagnetic detector at the door into the magnet room is the only place where both existing operations and available space will permit.

But if the door to that room swings out (as is currently recommended by the majority of MRI equipment manufacturers), can you put the detector on the other side of the doorway; on the inside of the MRI scanner room? Physically, yes, you can put the instrument there. Physically, you could also use your MRI scanner room as a waiting area for patients with unknown medical implants and devices, but both ideas would have grave dangers.

The intention of ferromagnetic detection is to alert you to the presence of magnetically attracted materials before they get close to the magnet. Placing a ferromagnetic detector inside the room would only be less effective if were mounted at the face of the bore of the magnet.

Since it often takes a moment to react to the alarm of a ferromagnetic detector, the step or two that a person may take past the ferromagnetic detector isn’t typically a problem outside the MRI scanner room, but in the room where inches can make enormous differences in the magnetically attractive effects, those couple steps can make the difference between avoiding an accident or cleaning-up after one.

Couple the compromised effectiveness with the fact that – at one time or another – everything needs servicing, and you’ve introduced another object into the MRI scanner room that may necessitate servicing from workers with tools. The attempt at increasing safety has actually introduced a new opportunity for accidents.

Lastly, MRI equipment manufactures are (justifiably) nervous about the introduction of equipment into the room which supports the MRI scanner. Does this other equipment emit RF noise that might interfere with the MRI images? Is it going to compromise the function of the scanner? Will the magnetic fields of the scanner adversely effect the other equipment?

In response to these concerns, MRI equipment vendors typically prohibit equipment or devices that haven’t been tested and deemed non-disruptive. Even just placing a ferromagnetic detector inside the MRI scanner room would very likely void significant portions of your MRI manufacturer’s warranty.

The fact is that there are often alternate locations for siting of a pass-through ferromagnetic detectors. It may take a little creative thought or a willingness to slightly modify operational protocols, but typically there are a handful of possibilities for each site. There is no reason – whatsoever – to place a ferromagnetic detector inside the MRI scanning room, and it is extremely ill-advised to do so.

Tobias Gilk, President & MRI Safety Director
Mednovus, Inc.

MRI Patient Pre-Screening

Ferromagnetic detection is a vital part of the pre-screening for persons about to enter the MRI magnet room, but it’s only one part of the overall sequence.

First, before we jump into the issue of where in the sequence ferromagnetic detection is best deployed, it’s important to break pre-MRI screening into its two constituent parts: clinical screening and physical screening.

Clinical Screening:

Before being brought to the MRI magnet, everyone (and this means patients, visitors and staff) needs to be screened for contraindications. Most often we think of pacemakers, but other contraindications include nerve stimulators, insulin pumps, prosthetics, halo vests, and a number of other objects. The screening is typically accomplished through the use of forms to help the subject identify any clinical risks for the MRI provider. The screening form is then to be reviewed between the patient and the MRI Technologist.

Once clinically cleared of contraindications for the MRI exam, then the subject should proceed to the next step…

Physical Screening:

Contrasted with the widespread uniformity of the clinical screening, the physical screening takes very different forms at different provider. However, all have the same objective, namely, to remove ferromagnetic materials from the subject and keep them away from the MRI scanner. Even small quantities of ferromagnetic material can cause artifacts in the MRI scan when near the imaging volume. Small ferromagnetic items, such as bobby pins and nail clippers, have caused serious harm when propelled by the magnetic force of an MRI magnet. And obviously, large items such as oxygen cylinders and floor polishers can have catastrophic consequences if brought to the MRI room.

Some MRI providers have outpatients simply empty their pockets, others provide gowns or scrubs for MR patients to change into, and all should use ferromagnetic screening to help verify patients’ compliance with screening instructions.

When performed in the above order, providers avoid gowning patients only to find out that the patient can’t receive the MR exam. Additionally, when clinical screening is accurately completed first, the Technologist has done everything within his or her human capabilities to mitigate the contraindication risks associated with exposure to magnetic fields. Although it is impossible to completely eliminate the chances of accidents, by following the recommended industry-standard procedures of  conscientious clinical and physical screenings followed by properly-performed ferromagnetic detection, the safety of your MRI center has been significantly enhanced.

Some of the most sensitive ferromagnetic detectors currently available use passive magnetic fields to improve sensitivity. These GS (Greater Sensitivity) detectors use a localized DC field (i.e. stronger versions of a similar type of the permanent magnet that holds your notes on your refrigerator door). While the magnetic field strength very close to the GS detector can exceed the 5-gauss threshold, that limit is for persons who haven’t been successfully cleared for MRI contraindications (a step which was just completed if the pre-MRI screening was conducted in the proper order).

While patients and caregivers should be concerned about exposing unscreened persons to the extraordinarily powerful magnetic fields around the MRI, momentary exposure of post-screened persons to the passive “fridge-door” magnetic fields of a GS ferromagnetic detector is very, very small on the relative risk-o-meter. And this minute risk comes with an enormous potential safety upside…

No ferromagnetic detection system on the market from any manufacturer is intended (or approved) for finding objects internal to the body of the patient. However as an incidental finding, ferromagnetic detectors have alarmed on the ferromagnetic content of implants (including pacemakers) that were disavowed by the patient in the clinical screening process. While ferromagnetic detection should never be used in lieu of conscientious clinical screening, they have helped to identify critical contraindications that may have otherwise jeopardized the safety of the MR patient — had they not been found by the ferromagnetic detector.

And the relative risk of being exposed to 5, 10 or even 100 gauss as a part of a physical pre-screen (particularly when already cleared of clinical contraindications) is microscopic, when compared to either the risk of the planned exposure to 15,000 / 30,000 gauss, or the potential benefit of identifying a contraindication that the patient themselves didn’t communicate.

The take-home messages from this are these:

  • MRI providers should provide as thorough and comprehensive clinical screening as humanly possible for everyone approaching the MRI.
  • Once the clinical screening is complete, the provider’s standard physical screening (emptying pockets, changing into scrubs, etc…) should be conducted as appropriate to the MR patient / visitor.
  • And following the clinical and physical screenings, patient / visitor compliance should be verified with a ferromagnetic detector.
  • If these industry-standard procedures are correctly followed, there should remain only minute (accepted) risks associated with exposure to any magnetic field, either the enormous field of the MR or the comparatively tiny field present in GS detectors.

Clearly, providers should feel free to use whatever ferromagnetic detection they wish – from their choice of manufacturer – in order to conform with ACR, VA and Joint Commission guidance, whether it be an instrument which relies on only the trace-magnetism of the Earth’s own magnetic field, or one in which the detection sensitivity has been enhanced through the use of a locally-provided, passive DC magnetic field as found in GS ferromagnetic detectors.

My recommendation is always to use a detector with the greatest possible sensitivity. Because, while they are wonderful instruments that can make a substantial improvement in a provider’s MR safety protocols, ferromagnetic detectors are dumb. They can’t differentiate ‘good’ ferromagnetic material from ‘bad’. These sorts of value judgments should be made by a trained MR technologist and not by a machine.

In my opinion, ferromagnetic detectors should be used to help find every piece of ferromagnetic material that they can, so that the Technologist knows what is about to enter their magnet room (and can make re-screening decisions as appropriate). The greater the sensitivity of the detector, the more informed those Technologist decisions will be.

Pass-through ferromagnetic detection systems, such as the newly released Mednovus Sentinel® GS 2.0 portals, also have user-adjustable sensitivity settings, so that the system can be ‘dialed back’ as needed for special circumstances, further supporting the concept of having the instrument with the greatest sensitivity, and tuning it to meet your specific needs.

As evidenced by repeated, and increasing MRI projectile accidents, there is enormous room for improvement from the prior standards. Effective pre-screening of MRI patients, including the use of ferromagnetic detection at the appropriate point, can make an significant difference in the safety of the MR exam. Providers should turn to the current best practice guidance and compare their pre-MRI screening processes, making any indicated changes to help assure the safety of their patients, visitors, and staff.

Tobias Gilk, President & MRI Safety Director
Mednovus, Inc.

Dr. Emanuel Kanal Recommends Ferromagnetic Detection

If you ever get a chance to hear Dr. Kanal speak, GO! Apart from being Director of MR Services for the University of Pittsburgh Medical Center, a Fellow of both the ISMRM and the ACR, Chair of the ACR’s MR Safety Committee and one of the world’s experts in instruction for the mind-boggling complexity of MR physics, you’ll also find him to be one of the most animated, enthusiastic and downright approachable speakers, ever.

That’s precisely what about 100 – 200 Radiology Administrators at the AHRA Annual Meeting, held just a couple weeks ago in Denver, found out in Dr. Kanal’s MRI Safety Update presentation.

His talk whisked through a number of topics in the brief hour that he had, but one of the chief subjects of his presentation was his enthusiastic support for the use of ferromagnetic detection (FMD) systems as a quality assurance step to assure patient compliance.

At his direction, the University of Pittsburgh Medical Center (UPMC) has purchased 20 Mednovus SAFESCAN® hand-held Target Scanners™, which are in use throughout the UPMC system. Dr. Kanal’s MRI suite is also the ‘proving grounds’ for ferromagnetic detectors from different vendors and he highlighted the use of the Mednovus Entry Sentinel® GS walk-through portal, which is currently being used in a trial to verify screening compliance.

In the coming days and weeks, I hope to share with you specific excerpts from Dr. Kanal’s presentation to the AHRA annual meeting. Suffice it to say that the world’s foremost authority on the breadth of MRI safety issues is a firm believer that MRI-projectile accidents are among the most common source of MRI-related injury – and that ferromagnetic detection can be a remarkably effective tool to help minimize these most frequent safety lapses.

Stay tuned for more information from Dr. Kanal’s presentation, coming soon.

Tobias Gilk, President & MRI Safety Director
Mednovus, Inc.

Not ‘Metal Detector’ But ‘Ferromagnetic Detector’

What a metal detector actually does is pretty self-evident by the name of the product… it detects metals. If you’re looking for gold doubloons on the beach or trying to find an underground gas pipe, a conventional metal detector is what you want. But if you’re screening people and objects before they go into the room with the giant magnet at the heart of a magnetic resonance imager (MRI), you’re likely concerned about finding those things  – like pocketknives, cell phones, iron-containing jewelry, wheelchairs, medical gas cylinders, etc… – that can be attracted to the magnet with such force that they can fly across the room.

Click To Read More About What We Look For And What These Instruments Find…