MRI Monitor: An Ounce of Prevention
By Kevin Brinkman
Vol. 20 No. 11 P. 8
Monitoring magnet health can keep your MRI department fit.
“The devil is in the details.” That assertion can be directly applied to the important work of medical imaging engineers, particularly when it concerns the tasks of preventive maintenance and monitoring MRI equipment.
MRI is groundbreaking technology that has opened new windows into the human body while helping health care providers make important and often lifesaving diagnoses to millions of people every year. Utilizing the power of superconducting magnets, MRI systems are able to do all of this without exposing patients to ionizing radiation.
When an MRI system experiences downtime, the potential for negative consequences is far reaching. For example, patients may be forced to reschedule, which could mean waiting for sensitive news about their health and well-being. Such delays often prompt them to seek care at other facilities.
MRI system downtime disrupts operations inside health care facilities as well. There will be lost revenue along with administrative costs associated with the downtime. In addition, health care organizations will continue to incur the cost of running the MRI machine’s chiller, even as it sits inactive.
Of course, MRI downtime affects field service engineers (FSEs) from third-party service organizations and in-house medical imaging departments, too. It interrupts scheduled service and planned maintenance because addressing the downtime becomes the priority. What’s worse is that failing to monitor MRI magnet health can erode trust between engineers and health care organizations. For FSEs, it could mean damaging relationships with important clients, while in-house engineers may shoulder much of the blame for the downtime.
These are just a few of the reasons why it pays to have engineers keep a close eye on MRI systems, especially the equipment’s magnet health.
Preventive maintenance procedures can seem mundane, but glossing over scheduled preventive maintenance can lead to bigger problems down the road. The goal is to catch potential problems before they occur so that health care facilities avoid costly downtime.
Among the most important preventive maintenance tasks are cleaning primary and secondary water filters and strainers while checking for clogs. A clogged filter or strainer can impede chilled water flow, which may result in the magnet refrigeration (MREF) compressor overheating and possible failure.
Imaging engineers should also pay attention to the MRI system’s adsorber. It should be replaced as the system nears 20,000 scan hours. Adsorbers only let helium into the MRI’s cold head. They filter out oil and other substances, preventing them from contaminating coolant lines in the system.
Magnet Health Vital Signs
Beyond scheduled preventive maintenance, imaging engineers should consistently monitor other factors that indicate the health of an MRI system’s magnet. Imaging engineers can use convenient remote monitoring solutions that alert them to critical issues when readings go outside specified parameters. Closely watching and listening for signs can help imaging engineers and others identify issues before they cause downtime.
Even before a system fails, poor magnet health can cause image artifacting, which complicates efforts to make accurate diagnoses. Ignoring warning signs of magnet health could also cause unanticipated part failures and costly helium loss.
The superconducting magnets that MRI machines use need to stay extremely cold in order for the system to function as intended. Liquid helium is used as the coolant, keeping the magnet coils at a temperature below 10 degrees Kelvin. That’s made possible by the MRI coldhead, which is a device that condenses helium into liquid form. Because the coldhead is constantly running, the device slowly loses cooling capacity, eventually wearing out and requiring a replacement. Engineers should monitor the recondensing margin to ensure that coldhead performance is up to original equipment manufacturer (OEM)–specified standards.
Another effective way to spot problems with the coldhead is to use your ears. Changes in the way this device sounds are a dead giveaway. Coldheads make what’s often described as a “chirping noise.” If an engineer or technologist notices the pitch of that noise changing, the coldhead should be examined.
The MREF compressor does the job of pumping liquid helium through the system, somewhat similar to the way the heart pumps blood through the body. Engineers should regularly monitor its dynamic and static pressure to ensure good magnet health. Numbers representing adequate pressure will vary depending on the MRI system. When static or dynamic pressure isn’t up to spec, it may cause the coldhead to operate inefficiently, which will result in a loss of helium. Replacing the coldhead, helium lines or possibly the entire compressor assembly can be expensive, so make sure the MREF compressor is delivering proper pressure.
Helium itself is an extremely important consideration for medical imaging departments. The current international shortage of this element is having a direct impact on MRI machines. Keeping track of helium fill levels for MRI systems is of utmost importance. Facilities are waiting two to three weeks for helium providers to deliver emergency fills, so it’s wise to closely monitor these levels and be proactive about scheduling helium fills in advance to avoid MRI downtime. For example, if a system’s minimum helium level is 50%, scheduling a fill when the level drops to 60% would decrease the risk of downtime as well as the possibility that lack of adequate helium would cause inhomogeneity and impact image quality.
The helium shortage has also caused prices for the coolant to skyrocket. Poor MRI magnet health can lead to increased helium boil-off. If the system is running too hot, more liquid helium turns to gas and escapes. Maintaining magnet health prevents helium loss and will ultimately save the facility money.
The bottom line is imaging engineers need to stay informed and aware to ensure MRI magnet health is optimal. Whether a facility is under a service contract with the manufacturer, using an independent third-party service organization, or has imaging engineers on staff, it needs experts who have been well trained on its specific MRI system or systems to ensure that the precise calibrations for particular OEMs and models are used.
It’s also important to work with supply chain partners who can be relied on in the moment of truth because there will always be times when even the most vigilant imaging engineer will have to troubleshoot an unexpected problem. The more informed an engineer is about the system, the easier it will be to solve and fix problems.
— Kevin Brinkman is the senior director of engineering for Technical Prospects. He serves as an expert in Siemens Medical Imaging parts and equipment and works to lead product repairs and quality assurance testing while also managing Technical Prospects’ team of engineers.