On Friday, March 6th, an MRI machine exploded at an animal hospital in Paramus, NJ. According to reports, before the explosion the 10-year-old MRI was being disassembled by three workmen so that a new unit could be installed. The three workmen were injured, one critically. No hospital staff or animals were injured as they were in a different part of the building.
We asked Veterinary Imaging of the Chesapeake's Chief of Imaging, Kevin C. Stevens, AART, RT (R)(MR) to give us some context so we can better understand what might have happened and what is the risk of this happening in the future.
"First of all I should explain that our situation at VIoC is quite different from that in Paramus, NJ, and we see little danger of a similar incident here. Our MRI is monitored daily and serviced monthly by a team of professionals as part of our quality control. Our MRI is housed outside the Chesapeake Veterinary Referral Center in a trailer, away from specialists' offices and treatment areas.
"That said, we have seen instances like this before in which a scanner is being decommissioned and there is some catastrophic failure in the process causing an 'explosion.'
"It's not an explosion in the traditional sense of the word. What generally happens is that the technicians begin ramping down the electrical current in the magnet and depleting the liquid helium to make it 'safe' for removal and transport. In the process, the magnetic field and state of the electromagnet become extremely fragile. For one reason or another, either too much heat is generated in the magnet and there is not enough cryogen to cool it, or they decrease the electrical current or the cryogen too quickly, and the field spontaneously collapses, causing the magnet to quench and release all of its cryogen and energy.
"When this happens the liquid helium that is left, which must remain below 4 degrees Kelvin, begins to boil off rapidly. The liquid helium turns to a gas and expands to 757 times its volume. If there is any failure in the emergency ventilation system for the rapidly expanding gas, it will back up in the cryogen chamber of the magnet and increase in pressure until the chamber ruptures violently. These events have been known to destroy an area from the size of the MRI suite to the entire building, depending on the amount of cryogen contained in the system.
"Though they are violent, these events are extremely rare and generally happen when a magnet is being moved, refilled with cryogen, taken apart, or put together for the first time. This is all the more reason why it is important to maintain regular service and preventative maintenance on the magnet and have expertly-trained staff in place when servicing the magnet. It's also important, as in the case in New Jersey, to make sure there are no patients or non-essential personnel in the vicinity when servicing the magnet."
If as a referring vet, you or your clients have any questions or concerns about MRI, please contact Kevin at firstname.lastname@example.org.