Yes, I think I’ve written at least twice before about the imminent start of the trial for the civil lawsuit stemming from the Michael Colombini fatal MRI accident in 2001. And, yes, I was wrong both times before. So, I would expect nothing less than readers of this entry to take my 3rd prognostication of the start of the trial with something more than a grain of salt… perhaps an entire salt lick! But today a little birdie told me that there’s a hole in the otherwise-booked New York Supreme Court trial schedule for late October / early November and the Colombini trial may just fit right in there.
RT-Image brought a stack of their August 3rd issue to the AHRA and handed them out at the MRI safety presentation. Why (apart from general publicity)? Because the primary thrust of the issue was on many aspects of MRI safety. This issue has feature articles on the new MR Conditional pacemaker, infection control in the MRI suite, and even one that I wrote for them…
One of the most oft-cited rationalizations for not complying with contemporary best practices that call for using ferromagnetic detection (FMD) for MRI pre-screening is that ‘FMD doesn’t catch anything that existing screening protocols aren’t meant to catch.’ What you may find surprising about this statement is that I agree with it wholeheartedly… I would just change the inflection a bit. I would say it more like…
Ferromagnetic detection doesn’t catch anything that existing screening protocols aren’t meant to catch.
That inflection makes a world of difference, as you’ll see in just a moment…
A few weeks ago I posted my layperson’s summary of why there’s even an issue with metal and MRI (click here to read that post on MRI and Metal). In this posting, I hope to explain why it’s so critical to find metals, particularly ferromagnetic metals, being carried by people or inside objects.
Many people just learning about MRI safety and hazards ask very similar questions. One of most frequent is, “why do I have to remove all metal before an MRI,” or it’s corollary, “can I get an MRI with some metal on (or in) me?” To answer these questions, let’s start at the very beginning… What A Very Good Place To Start… (Click Here)
‘NEWS FLASH: Large icebergs may present grave hazards to ocean liners.’
No, that’s not what the FDA just said, but the news in the FDA’s most recent alert is almost as dated as my hyperbolic example. What the FDA did in their March 5th alert on the MRI safety of transdermal medication patches was essentially … Click to find out what the FDA’s alert ‘essentially’ did…
The ECRI Institute has again published their annual Top-10 Health Technology Hazards document for 2008, which is available as a free download from their website. Number 9 on the ECRI list is one of the well known MRI hazards. But before I tell you which MRI hazard made their list, let me give you a little background on what the ECRI Institute is and what they do…
In short, no. Hand-held magnets do not do the same job that ferromagnetic detectors do.
In many MRI facilities, foreign materials brought by people to the MR suite are tested for magnetic field hazards with high strength hand-held magnets. Ones designed specifically for MRI screening are far stronger than the ones holding up my daughter’s artwork on my refrigerator. Some of these ‘test’ magnets can be 1 Tesla at the surface (10,000 gauss)!
These extremely powerful hand-held magnets can help users differentiate between superficial materials that are, and are not, ferromagnetic, but the extraordinary strength of these magnets introduces a number of additional cautions which limit their use.
First, the key word in the paragraph above is ‘superficial.’ The magnetic field of all permanent magnets drops off precipitously (field strength drops with the cube of distance… double the distance and the magnetic field is cut to 1/8th the original value), so permanent magnets will be useful for distinguishing ferromagnetic materials only at or near the surface of an object. Ferromagnetic components below the surface may go undetected by a hand-held magnet, but rest assured that the MRI will find them if those objects make it into the scanner room!
Second, the potential forces exerted on a ferromagnetic body with magnetic field strengths of near 1 Tesla mean that shallow ferromagnetic material within the body of the patient could be moved, perhaps dangerously, by these very strong magnetic forces. But if the purpose of screening is to prevent accidents instead of preemptively causing them, hand-held magnets are poorly suited for patient screening.
Third, if screening medical equipment instead of patients, even some pieces of equipment designed for use in MRI scanner rooms have maximum allowable static and dynamic magnetic field values. Sticking a 1 Tesla magnet all over an anesthesia machine may wind up having some unintended consequences with regard to operation.
Lastly, 1-Tesla magnets stick hard to things. While the hand held magnets aren’t weighty, their magnetic force can require a bit of elbow-grease to get them separated from the cart or medical gas cylinder to which they got stuck. No, it’s not like it becomes epoxied on, but wielding one of these high strength permanent magnets is not a trivial affair.
Each ferromagnetic detection product has its own limitations, so I’m not attempting to state that FMD systems are the perfect solution to the hand-held magnet problem. Hand-held magnets can be useful, in a limited range of uses.
When it comes to the recommendations of the ACR Guidance Document for Safe MR Practices, or the Joint Commission Sentinel Event Alert (#38) on MRI Accidents and Injuries, or the U.S. Veterans Administration’s new MRI Design Guide, the experts all seem to have recognized the benefits of ferromagnetic detection and made a clear distinction between the new technology and the old custom of using permanent magnets to test for safety.Tobias Gilk, President & MRI Safety Director Mednovus, Inc. Tobias.Gilk@Mednovus.com www.MEDNOVUS.com