By Kathryn Doyle
NEW YORK (Reuters Health) - Hospital and research staff who work in rooms with magnetic resonance imaging (MRI) machines sometimes report experiencing vertigo, a metallic taste or nausea, according to a new study.
Patients undergoing MRI scans don’t need to worry about these symptoms, because they are caused by the magnetic field created outside the scanner when it is turned on, said Hans Kromhout. He worked on the study at the Institute for Risk Assessment Sciences at Utrecht University in the Netherlands.
“Patients are not going to be exposed to these effects, and most people are only scanned a relatively small number of times in their lives,” he told Reuters Health.
Kromhout said the exact reason healthcare workers and technicians sometimes experience MRI-related symptoms is still not clear. One possibility is that moving around the room through the changing magnetic fields results in currents in the inner ear or brain.
He and his team studied 361 employees at 14 MRI facilities in the Netherlands. The employees filled out diaries for shifts they worked inside and outside the MRI facility, reporting any symptoms they experienced during each shift.
The researchers predicted that vertigo, nausea, ringing in the ears, metallic taste and seeing spots could be related to working around the MRI machines.
Among staff members who either never worked with MRI machines or weren't working with them on a particular day, only one percent reported experiencing one of those symptoms. That compared to 29 percent of staff members who were working with the strongest MRI machine, a 7 Tesla scanner.
For both the MRI-exposed group and the comparison group, few people experienced other symptoms, like earaches or hot flashes, which would have probably been unrelated to the scanners, according to results published in Occupational and Environmental Medicine.
Among the symptoms the researchers expected to be linked to MRI machines, vertigo and a metallic taste in the mouth were the most common. Employees reported vertigo during six percent of all work shifts involving MRI scanners.
These symptoms were more common among people who worked with more powerful scanners.
“The higher you get exposed, the more frequently these symptoms will occur,” Kromhout said. “In themselves these symptoms are not hazardous, but you have to realize that it’s not very good for your well-being to be nauseous on the job.”
Newer MRI scanners are much more powerful than those commonly used a few years ago, and the scanners will continue to be made more powerful and to be used more often in the future, he said.
“More and more people will start complaining about their situation because that’s what we’re seeing,” Kromhout said.
Researchers have known for some time that these types of short-term symptoms could happen around MRI machines, but mostly from anecdotal reports.
This new study, though it demonstrates the connection systematically, does not add anything new to what researchers know, Frank G. Shellock, who was not part of the research, told Reuters Health by email. Shellock is the Director for MRI Studies of Biomimetic MicroElectronic Systems at the National Science Foundation's Engineering Research Center at the University of Southern California in Los Angeles.
It’s possible to decrease the risk of symptoms by walking more slowly toward the MRI machine, thus passing through the magnetic field it creates more slowly, Kromhout said. In the new study, some workers reported doing this and seeing a decrease in symptoms.
“In that sense people can take control of the situation,” Kromhout said.
Certain people seem to be especially sensitive to the magnetic fields and to experience more symptoms than others, but researchers aren’t yet sure how to identify them, he said.
“It would be good if we could get a figure behind that and tell workers that they will experience these symptoms,” he said.
Though the symptoms tend to be very short-lived, there is a chance workers could experience long-term health consequences from working with MRI scanners, a question Kromhout is investigating next.
SOURCE: http://bit.ly/1k5GUzn Occupational and Environmental Medicine, online April 8, 2014.