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
"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.
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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
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.
Occupational and Environmental Medicine, online April 8, 2014.
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