GE Healthcare MR coil courtesy of Innovatus Imaging

Tips for keeping your MR coils in top working order

September 08, 2021
by Lisa Chamoff, Contributing Reporter
MR coils are one of the keys to high-quality MR imaging. The delicate pieces of equipment are also heavily utilized and in close contact with patients, so it is important to disinfect them regularly.

We asked service professions what they recommend for ensuring coils have a long, healthy life.

Precious cargo
In general, coil lifespan is in direct proportion to the level and care of handling that is employed in the department, said Ted Lucidi, clinical marketing and commercial specialist at Innovatus Imaging.

“Recently, MR coil design has been enjoying significant technological advancements. Today’s newer coil designs are light, flexible, and form-fitting. They are multipurpose and some employ fiber optics. All of these technical advancements lead to coils that are much more fragile than traditional coil designs,” Lucidi said.

Most MR coil failures are a direct result of, or are related to mechanical damage or trauma, according to failure analysis data amassed by Innovatus, with more than 35% of all coils presenting with mechanical damage due to trauma and an additional 18% related to trauma and/or improper use.

“The remaining 47% of coil failures may be considered related to general wear, electronic failures or unknown reasons,” Lucidi said. “To extend the life of an MR coil, it’s recommended to partner with an organization that is able to actually restore the coil’s life cycle and reset the timeline versus merely offering a repair.”

End users should always ensure they handle coils properly — by lifting from the base. Often, volume coils, such as head and knee coils, get broken by lifting from the top cage, said Ray McClellan, president of MRI Technical Services Inc.

“Many coils are bulky, heavy and fragile,” McClellan said. “Lifting [or] moving them by just grabbing any available handle can cause physical damage, and oftentimes the easiest way to pick them up is the most damaging.”

Technicians should take care when plugging coils into their connectors.

“Take care not to insert or remove connectors at an angle,” McClellan said. “All of them have keys for proper alignment, but if you try hard enough you will bend pins and break housings.”

Take care in how cables are positioned.

“Many coils come in with internally broken wires in the cables from repeatedly being bent too sharply in the same place,” McClellan said. “When scanning, try to position cables in the least stressful position available in accordance with the OEM safety recommendations.”

For larger coils, like the spine coils, users should take care during storage not to sit the coil upright so the full weight of it is on the cable, McClellan said. This also causes internal broken conductors.

Technicians should also make sure not to let the cables drop and hit the floor when moving or carrying the coils.

“Many coils have RF traps on the cables and sudden shock can cause internal damage that can lead to coil heating and failure,” McClellan said. “For flex coils, avoid sharp bends in the coils when strapping around the patient. Just like tight cable bends, consistently folding flex coils at sharp angles in the same places will eventually break the internal conductors and cause the coil to become intermittent or to fail completely.”

It is also critical to not leave coils, or unused coil sections, that are not connected sitting anywhere near the magnet bore while scanning. They must be plugged in to decouple from the transmitted RF, and can inadvertently be damaged if they are close enough,” McClellan said.

It’s important to read — and believe — the instruction manual, McClellan said.

“Many coils that are working properly are sent in with the complaint of patient heating,” McClellan said. “The truth is that nearly all coils dissipate significant amounts of heat during a scan. Manufacturers have many dos and don’ts about proper coil, cable and patient positioning in order to minimize and manage the heat that is produced. Excessive heating or even burning a patient is not always the fault of the hardware.”

Facilities should establish a well-communicated set of policies and best practices.

Clear policies “are the best methods of addressing failures within user control,” Lucidi said. “These would span practices related to periodic inspection, proper storage, transportation, patient placement, and cable routing practices as well as proper cleaning and disinfection processes.”

Proper storage is also important.

“Keep coils clean and stored in an individual storage location,” said Charlie Lewis, director of technical support operations for The Imaging Solutions Company. “Stacking them on a chair or the floor is not conducive to proper handling procedures.”

Regular MR service, within the manufacturer’s operational specifications, is also important for coils.

“A correctly calibrated machine doesn’t put any undue electronic stresses on the equipment,” Lewis said. “Request signal to noise ratio data on each coil to document and track coil performance. The end result will be a superior imaging product with minimization of early onset failures due to electronic stresses.”

Cleaning and disinfecting
Each OEM has its own specific recommendations for cleaning and disinfecting their items that come into contact with the patients, and service professionals recommend adhering to those guidelines.

In general, manufacturers recommend cleaning all coils with a soft cloth and a mild soap or detergent solution before disinfecting.

McClellan notes that Philips recommends using either a 70% solution of isopropanol or ethanol alcohol or a solution of 0.5% chlorhexidine in 70% ethanol, which are considered "intermediate" disinfectants.

While the same procedure is recommended for both hard-surface and closed-cell soft coils, such as urethane plastic or foam covered flex coils, the latter coils should be inspected carefully to make sure there are no breaks in the surface. If breaks occur, the underlying open-cell foam cannot be disinfected and so the coil should be replaced, McClellan said. A black-light flashlight can be used to help highlight any biological contamination, such as blood and other bodily fluids.

Coils that are being disinfected using alcohol solutions should be air dried, while chlorine solutions require rinsing with a soft cloth and water before drying, McClellan said. Open-surface items, such as straps, can’t be disinfected, but they should be cleaned by washing them in a soap or detergent solution and then fully drying before use.

Endo-cavity coils require the same cleaning procedure, but the use of higher-level disinfectants such as Cidex OPA or Steranios 2% NG, and have their own specialized procedures to follow, according to McClellan.

Lucidi agrees that it’s best to check with manufacturers on cleaning and disinfecting coils.

“OEMs develop the design and can attest to which chemicals their materials are compatible with,” Lucidi said. “Likewise, manufacturers of chemical disinfectants can attest to the efficacy of their products through verification and validation. Management teams and infection control departments need to work together to find a balance between efficacy and compatibility.”

Innovatus provides guidance and consulting to its customers to help them identify potential options for OEM-approved chemicals and assess if the practices employed within the department align with OEM recommendations.

Commonly, manufacturers do not advise submerging any part of a coil or spraying or pouring cleaning agents directly onto a coil, which could damage the internal circuitry. They also recommend detaching a coil from the scanner before attempting to clean it.

A common recommended cleaning practice is to clean the coil with a cloth that has been dampened in a solution of 10% bleach and 90% tap water, or 30% isopropyl alcohol and 70% tap water.

Cleaning and disinfection agents are not one-size-fits-all.

“There are well over 1000 makes and models of MR coils and chemical compatibility, exposure times, and recommended practices can vary between models,” Lucidi said. “A best practice is to inventory the coil models in your facility and then determine the approved chemicals that are common between them.”

To ensure coils are properly sterilized while considering the lifespan of the equipment, Lewis recommends setting a standardized cleaning schedule that meets current CDC guidelines for patient contact and proving in-service technologist training concerning coil handling, cleaning, storage and operation.

Facilities should also evaluate coil and protocol usage on a regular schedule to assess needs and coil availabilities.

“Engage (a) service provider as a partner in the imaging chain,” Lewis said. “They are not only there to fix it when it breaks but to ensure the entire MR is operating to its potential and within the manufacturer's specification.”