Frequent MRI Scanner Exposure Might Affect Memory: Study

Magnetic field remains even when imaging not taking place

By Robert Preidt

Thursday, August 30, 2012

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THURSDAY, Aug. 30 (HealthDay News) -- Exposure to magnetic fields generated by MRI scanners may lower a person's mental skills, according to a small new study.
The effects were most noticeable in tasks that required high levels of working memory, which could have implications for surgeons and other medical staff who work within the vicinity of MRI scanners, the researchers said.
The study was published online Aug. 29 in the journal Occupational and Environmental Medicine.
Along with radio waves, MRI uses strong magnetic fields to obtain detailed images of the brain and spine, explains a journal news release. Three types of magnetic fields -- static, switched gradient and radiofrequency -- are used to create an MRI image.
Even when no imaging is taking place, the static magnetic field is always present.
Thirty volunteers completed the study. All were exposed to an MRI static magnetic field of zero, 0.5 (medium) and 1 (high). Each exposure was conducted one week apart. After each exposure, the volunteers were given 12 timed mental tasks to test the sorts of skills that a surgeon or other health care professional might use within the area of an MRI scanner.
The results showed that the medium and high exposures to the static magnetic field had a significant effect on general functions such as attention, concentration and visual and spatial awareness.
After medium and high exposures, volunteers took 5 percent to 21 percent longer to complete complex mental tasks, which rely on working memory.
"The exact implications and mechanisms of these subtle acute effects in [practice] remain unclear," wrote Professor Hans Kromhout, of Utrecht University in the Netherlands, and colleagues.
They noted that the introduction of increasingly powerful MRI machines has raised exposure levels to static magnetic fields for both patients and medical staff.
"To date, mainly health and safety concerns for patients have been evaluated, but possible consequences are particularly important for professionals ... cleaners and MRI engineers since they are repeatedly exposed to static magnetic fields," the researchers noted.
While the study found an association between MRI exposure and slower working memory, it did not prove a cause-and-effect relationship.

SOURCE: Occupational and Environmental Medicine, news release, Aug. 29, 2012

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