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Wednesday, November 09, 2011

MRI Safety and the FDA

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.

Costly projectiles
Projectile-related accidents also can be very costly. Gilk cited a study from the U.S Department of Veterans Affairs' National Center for Patient Safety, which conducted a cost analysis of a projectile accident. It found that such events have an average cost of $43,172 per occurrence, based on the expense to repair the MRI scanner and legal settlements associated with an injury to a patient or staff person.
The total did not include downtime for the machine and lost revenue. "If the hospital is making, on average, $650 to $700 on technical revenue per MR exam and the machine is down for three days, [the facility] will miss 20 to 30 exams over that time, and that gets very expensive very quickly in terms of lost revenue," Gilk added.
As for hearing loss, facilities should provide patients with earplugs to prevent ear damage, and instruct patients on how to insert them properly. It may sound like a simple task to insert ear plugs, but not everyone's outer ear anatomy is the same, and one size does not fit all.
Kanal added that adverse events can be prevented by establishing and maintaining consistent MRI safety education among healthcare practitioners so they are aware of the potential risks that could occur throughout the MR imaging process. In addition, there should be "adequate MRI site access restriction and supervision by MRI healthcare professionals over patients and other non-MR personnel," he said.
Training personnel
Training is a critical ingredient to reducing the number of accidents in the MRI environment. Shellock maintains the website, as well as a site for the Institute for Magnetic Resonance Safety, Education, and Research ( The website features safety information and streaming training programs for patients, nonmedical personnel, MRI technologists, and radiologists.
Training for nonmedical personnel, such as maintenance staff, housekeeping staff, and security officers, on how to conduct themselves in the MRI setting is just as important as it is for MRI technologists and radiologists. Nonmedical employees may not realize that an MRI scanner is always energized, or "on," and have been responsible for projectile and other accidents at some facilities.
Shellock said there are no data available to determine if nonmedical employees cause more projectile accidents than professional healthcare staff, but they do "make up a fair number of the problems that have occurred."
Education and training programs need to be conducted on a regular basis, and MRI facilities "have to make a concerted effort to train anyone who works in and around the MRI setting," Shellock added. "It has been our motivation to put together these comprehensive programs. Now it is a matter of disseminating the information and making sure people understand that these programs do exist and they are able to access them."
While the use of ferromagnetic detection systems to prevent projectile incidents is widely recommended, Shellock noted that there are no current data or peer-reviewed literature on the technology's efficacy. He and his colleagues are preparing to evaluate ferromagnetic detection systems to determine the benefits of their use.
The FDA's safety workshop also plans to consider the issue of MRI safety for patients with implanted devices. Inconsistencies in labeling information for those devices are a major concern, according to Shellock. "That can cause a lot of confusion, and we often see MRI technologists and radiologists who may elect not to scan the patient," he added. "That is a disservice to the patient."

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: or,


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