Airborne Wheelchair Makes Astonishing Collision into MRI

While every organization with an MRI has safety policies, there is still plenty of room for human error. One of MXR’s best customers recently had an unfortunate incident, and wants to remind everyone of the importance of reinforcing magnetic safety protocols. Please forward this page to your colleagues. 

They say a picture is worth a thousand words. How could this happen? The photo was taken of one of MXR’s customer's magnetic resonance imaging (MRI) scanner, and it tells the medical imaging story no one wants to hear. The demonstrated strength of a 1.5 tesla MRI magnetic field is clearly enough to effectively pilot a steel wheelchair, then swallow it. If you think this couldn't happen in your organization, read on. 

A Magnetic Experience

The technician had just completed an MRI scan of a disabled female patient. As the technician helped her to sit up and get off the machine, the patient’s well-meaning husband decided (not realizing the risk it represented) to help by wheeling the steel wheelchair into the MRI room. He didn’t get far. He wasn’t more than a couple of steps into the room before the wheelchair went airborne like a baseball into the MRI bore as the MRI magnet sensed metal it wanted to consume.  

Fortunately, the technician was able to protect the patient, but the technician herself suffered from an injured arm resulting from attempting to block the unstoppable shooting wheelchair from going into the MRI bore. Everyone was lucky, but the MRI equipment and wheelchair didn't fare well. The wheelchair hit the MRI unit with enough force that it damaged both the exterior fiberglass, and the interior of the bore.

Above: A front and back view of the steel wheelchair jammed into the MRI bore.

Underestimated MRI Magnet Strength

"There is a lot to learn from this mistake" says Ken Parr, MXR's National Service Director for CT, MR, and PET/CT. Unfortunately, the magnetic strength of an MRI machine is commonly underestimated. How powerful is an MRI magnet? A 1.5 Tesla MRI scanner’s magnetic field is roughly 30,000 times stronger than the Earth's own magnetic field, with one single Tesla of MRI field strength being the equivalent to 20,000 times the strength of the earth’s magnetic field. Even something as small as a paper clip could reach a terminal velocity of 40 mph when pulled in by a 1.5T magnet. According to Parr: 

We see something like this about four to six times per year. In most cases, we can use a winch to extract the item from the grip of the MRI's magnetism, but if we had tried that approach here, we would have likely brought the whole wall down. Instead, we had to demagnetize the system to extract the wheelchair before we could repair the system.

It took the MXR's MRI repair service team about a week and a half to get the customer back online. It wasn’t cheap either. This mistake cost the customer $65,000 (with roughly $10,000 solely being for the wheelchair extraction process) not counting the cost of downtime. The emergency repairs brought the customer's magnetic safety protocols into question. 

Above: The MXR repair team arrives to power down the MRI magnet, then remove the wheelchair from the clutches if the MRI.

MRI Safety Reflections 

While the likelihood of this missile event and other MRI safety mishaps are more common than you might think. In a study published by the Journal of the European Society of Radiology, only 38% of safety incidents were reported formally and members expressed the need for better MR safety education

Magnetic Field Screening

MXR’s experience has been that many facilities don’t have their magnetic screening policies ramped up to what is optimal. By our estimates: 

• Only about 5% of customers use a walk-through magnetometer, which would have prevented this incident.
• Only about 50% of MXR customers even use of a handheld ferrous metal detector, which only costs a few hundred dollars.  

Although some may see implementing the above screening tactics as an unnecessary expense, when you factor in that MRI projectiles can result in death, injury, or costly repairs, better magnetic screening protocols seem nominal relative to the added benefit.