From the October 2014 issue of HealthCare Business News magazine
MR Safe: This designation is very restrictive (and, as a result, there are very few devices that have it). In essence, an object with this label must present zero risk in the MR environment, regardless of magnetic field strength, RF frequency / energy used, or the time-varying magnetic fields. Objects with this label must be non-magnetic, non-electrically conductive, and non-RF reactive. This leaves a small palate of possible materials, including silicone, glass, and some plastics and ceramics. While many homegrown “MR Safe” labels persist, properly labeled “MR Safe” objects are quite rare.
MR Conditional: Any object constructed with metal, or containing wires/batteries, or with any electrically conductive elements must be minimally identified as MR Conditional. This means that virtually every device/appliance used in the MR suite that is intended to be able to safely go into the scanner room — from fire extinguishers to wheelchairs — should be designated MR Conditional. Unlike MR Safe, MR Conditional imposes restrictions on what constitutes safe use. These limitations can include field strength, magnetic spatial gradient, RF energy, and time-varying magnetic field. This means that two different objects with MR Conditional labels may not be appropriate for safe use under the same conditions.
Particularly if an MR suite has more than one scanner, it is important that MR Conditional equipment not only be categorized and labeled as such, but also that the specific conditions for safe use be identified on the equipment. It may be that a device is known to be safe/functional at 1.5T, but not at 3.0T. For a site that has MR systems with different field strengths, or magnetic spatial gradients, or gradient coil capabilities, it is essential that the MR Conditional conditions for each piece of equipment be readily available to the department staff.
MR Unsafe:
As the name suggests, some materials/objects demonstrate overt ferromagnetic properties that make them unsafe near the scanner. Many crash carts are made of steel and would give an entirely unintended meaning to ‘crash’ if they were brought into the scanner room.
That means equipment in the suite should be appropriately tested, and conspicuously labeled, so that department staff can immediately recognize the safety characteristics of materials within the controlled access area (a principle that should be extended to equipment known to be brought into the suite, such as ventilators or anesthesia equipment).
Despite our best efforts to screen patients/ visitors and restrict the access of untested equipment, every provider knows that there are always opportunities for things to slip through the process. Whether through deception or ignorance, potentially dangerous ferromagnetic materials regularly find their way into suites without the knowledge of the technologists. One of the newest tools to thwarting this risk is the use of ferromagnetic detection systems, required for many through the FGI codes.
