Ferromagnetic Projectile Accidents In MRI Suites Are On The Rise What Has Been Done To Reduce The Problem

Why FDA and ACR Are Concerned With MRI Safety?

Nearly everyone who works around magnetic resonance imaging (MRI) has heard of or experienced incidents involving ferromagnetic projectiles. As the number and strength of MRI scanners in the nation’s hospitals has increased from a handful, 20 years ago to about 10,000 today, ferromagnetic accidents have become more frequent. Some have caused serious injuries and even death.

“The proliferation of MRI equipment and significant increases in both magnet strength and spatial gradients… have increased the number of accidents occurring in the MRI suite. Each accident and close call puts patients and staff at risk and carries the potential of damaging, if not crippling, over a million dollars worth of imaging equipment.”
Tobias Gilk, M . Arch., a member of ACR’s MR Safety Committee –
(Patient Safety & Quality Healthcare, September/October 2006)

Many experts in the area of MRI safety believe that a major factor in the failure to address safety issues in the MR environment is a gross underestimation of the risk.

“…there is a strong ‘it couldn’t happen here’ mentality. …I don’t believe people are quite aware of the potential problems that can occur, the substantial severity that could occur.”
Emanuel Kanal, MD, FACR, FISMRM, AANG – (Good Morning America, abc News 08/22/05)

“Each scanner would have a serious accident about once every 5 years.”
Chaljub et al (From the Study of the University of Texas Hospitals)

Even with a doubling of MRI safety incidents reported in the 12 month period ending mid-2006 from the previous one-year period and despite the reporting requirements, it is believed that fewer than 10% of MRI accidents are reported. No one knows how many have truly occurred. However, MRI safety specialists say there is no doubt they are on the rise. More than half of the reported accidents involve ferromagnetic projectiles. This vast underreporting prevents imaging providers in using the much needed information to make effective decisions to prevent future accidents. Furthermore, it serves to stigmatize those who admit to having had MRI safety mishaps. Therefore, there is no learning from the past.

According to a survey performed by Dr. Chaljub and colleagues in 1999, which was sent out to 250 imaging facilities across the US asking about the occurrence of MRI-related accidents, 52% of responses reported airborne objects: a defibrillator, a wheelchair, a respirator, ankle weights, an IV pole, a toolbox, sandbags containing metal pellets, a vacuum cleaner, and mop buckets.

Risk Increasing Factors

A number of factors are contributing to the ferromagnetic projectile risk and its increase. Most of the below mentioned issues are listed in “The VA National Center for Patient Safety MR Alert” summary:

1. With the increased use of higher strength field magnets and self shielded magnets, the maximum force of attraction increases dramatically.
2. The increase of spatial gradients of the new active shielded magnets:
   • No gentle, slowly increasing pull to provide feedback of ferromagnetic properties
   • Maximum force much greater than for the same field strength unshielded magnet
   • Distance/Time to react to force can be shorter than reaction time
   • A 3T magnet with the same magnetic footprint as a 1.5T has four times the force
3. MRI magnets are always ON, therefore projecting the magnetic field, which can be as much as 60,000 times more powerful than the Earth’s, 24/7. Equipment and consumables that are “safe” 99% of the time become “unsafe” near MRI
4. The large invisible magnetic field that is projected by an MRI machine and extends in 3 dimensions cannot be touched, seen, smelled, or sensed in any other way.
5. Many objects that are “seemingly safe” and appear not to contain iron or any other ferromagnetic materials, for example, sandbags can contain ferrous materials even though one would not think so.
6. Non MR staff in MRI suite, for example, cleaning personnel or the family members accompanying patients.
7. Labeling on devices or in documentation can be confusing: “MR safe”, “MR not safe” and “MR conditional” - these terms are not intended to be used without further specifying the particular MR environment conditions where the devices have been tested.
8. Sharing imaging staff between different modalities. What can be safe in CT environment can become very dangerous in MR environment.
9. In case of emergency, if you need to shut off the MRI magnet, there can be health hazards and $20,000-$500,000 cost associated.
10. Combination of complacency, work-arounds for speed, and diffuse responsibility

Regulatory Actions

In July, 2007 the FDA’s Patient Safety News video program acknowledges the ongoing effort to combat accidents and injuries in the MRI suites. The FDA states: “Unfortunately this problem has not gone away. MR associated accidents, many of them life threatening or fatal are still occurring, causing continued concern in the radiology community.” Furthermore, the FDA recognizes and highlights the recently updated “ACR Guidance Document for Safe MR Practices: 2007”

“It’s important to have and read this document” – FDA.

This year a wholly rewritten document, retitled the “ACR Guidance Document for Safe MR Practices: 2007,” has been dramatically expanded to offer a new safety standard for MRI suites. Consistent with the proceeding issues of the 2007 guidance document, the ACR reaffirms the application of the four-zone principle in laying out MRI suites. Under this principle, a person must successfully complete sequential levels of screening before they are cleared to proceed from areas with zero risks associated with MRI magnetic fields to the MRI magnet itself.

It is important to note that the new standards were unanimously approved by all committee members, which includes professionals form a broad spectrum of specialties, such as: MR physicists, research/academic radiologists, private practice radiologists, MR safety experts, patient safety experts/researchers, MR technologists, MR nursing, National Electrical Manufacturers Association, the U.S. Food and Drug Administration (FDA), the American Society of Anesthesiologists, legal counsel, and others.

Descriptions of the American College of Radiology’s Four Zones:

One of the “ACR Guidance Document for Safe MR Practices: 2007,” updates concentrates on ferromagnetic screening. And now for the first time recommends the use of ferromagnetic detectors for all MRI facilities. The entire document can be accessed through these links:
http://www.ajronline.org/aheadofprint/AJR_06_1616.dtl or,
http://www.acr.org/mr_safety

Below are excerpts from this document regarding ferromagnetic detectors:
“… ferromagnetic detection systems are currently available that are simple to operate, capable of detecting even very small ferromagnetic objects external to the patient, and now, for the first time, differentiating between ferromagnetic and nonferromagnetic materials. While the use of conventional metal detectors is not recommended, the use of ferromagnetic detection systems is recommended as an adjunct to thorough and conscientious screening of persons and devices approaching Zone IV. It should be reiterated that their use is in no way meant to replace a thorough screening practice, which rather should be supplemented by their usage.” (Page 4)

“Ferromagnetic detection systems have been demonstrated to be highly effective as a quality assurance tool, verifying the successful screening and identifying ferromagnetic objects which were not discovered by conventional screening methods. It is recommended that new facility construction anticipate the use of ferromagnetic detection screening in Zone II and provide for installation of the devices in a location which facilitates use and throughput. Many current ferromagnetic detection devices are capable of being positioned within Zone III, even at the door to the magnet room; however, the recommended use of ferromagnetic detection is to verify the screening of patients before they pass through the controlled point of access into Zone III.” (Page 21)

Kopp Development and Its Contribution to MRI Safety

Shortly after the most notorious accident at Westchester Medical Center in Valhalla, NY, where a 6 year old boy was killed by airborne oxygen cylinder while undergoing MRI procedure, Kopp Development Inc. began development of their product FerrAlert™, a ferromagnetic detection system.

What is FerrAlert™ and why is it essential for MRI safety?

Unlike conventional metal detectors, which detect many different metals, FerrAlert™ alarms ONLY upon detection of ferrous metals, and helps to pinpoint the location and mass of the offending object. FerrAlert™ not only helps to prevent injuries and mortality, but also prevents incidents that require quenches which can involve costly litigations. FerrAlert™ can also prevent image artifacts and increase patient throughput.

On May 25th, 2005 a Scientific Paper on FerrAlert™ was presented at the ASNR 43rd Annual Meeting. It was co-written by Emanuel Kanal, MD, FACR, FISMRM, AANG and Steven Thomas, MD and describes the very favorable results obtained from their study of FerrAlert™. With the help of FerrAlert™, 44.3% of patients were detected to still have ferromagnetic objects on their persons after fully passing through the standard existing screening procedures by the professional staff.

FerrAlert™ comes in two applications, ENTRY and PRESCREEN.

ENTRY reduces the risk of ferromagnetic projectiles from entering the MRI magnet. The device is installed unobtrusively at the approach to the MR magnet room, (Between Zones II and III of the ACR recommendations), or near the magnet room doorway. This product can significantly help to protect your investment in the magnet and to avoid a catastrophic accident, usually caused by large ferrous projectiles.

“Many current ferromagnetic devices are capable of being positioned within Zone III, even at the door to the magnet room…”

ACR Guidance Document for Safe MR Practices: 2007, Page 21

PRESCREEN is a highly sensitive unit that detects very small ferrous objects, down to the size of a hairpin, or single staple. The recommended placement for this device is in the patients’ screening or locker-room area, away from the magnet room. This product helps to increase patient throughput and helps to prevent potential misdiagnosis.

“…ferromagnetic detection systems are currently available that are simple to operate, capable of detecting even very small ferromagnetic objects…”

ACR Guidance Document for Safe MR Practices: 2007, Page 4

Both products are passive and emit no RF or magnetic field. Therefore, FerrAlert™ will not interfere with any other devices or the imaging process, and is safe for the patient with passive or active implants.

Both products are provided with the motion detector. Therefore, FerrAlert™ alarm only on the ferrous objects that are passing through the portal, while, stationary ferrous objects or near by traffic remains ignored. This feature allows product to concentrate on the immediate threat and helps to eliminate false positive alarms.

As of June 1, 2007 the original FerrAlert™ products have been superseded by a new line of the ferromagnetic detectors, FerrAlert HALO™ Series. This new generation of ferromagnetic detectors is based on the highly successful predecessor, adding features and increased sensitivity.

FerrAlert HALO™ - Operation & Installation easier than ever:

• New position indicator LEDs right on the portal pinpoint the location of the offending ferrous object
• Audio and visual alarm gives immediate feedback of an imminent ferromagnetic threat
• New adjustable portal width allows for a flawless, custom fit installation
• The wider PRESCREEN clearances allows for inpatient screening when used with truly non-ferromagnetic patient transportation
• PRESCREEN swing away option allows the portal to be stored within 4in from the wall
• Easily interpreted by all levels of personnel

As the industry leader in Ferromagnetic Detection for MRI Safety, Kopp Development Inc. has a proven track record. With over 100 units in the field, FerrAlert™ has been integrated in well-known medical centers, as well as in many smaller imaging facilities.

All the supporting documents mentioned in this editorial can be accessed through the Kopp Development’s website: www.koppdevelopment.com