MRI workers experience transient neurocognitive effects

Sep 10 2012

By Lynda Willams, Senior medwireNews Reporter

Individuals working in the vicinity of magnetic resonance imaging (MRI) machines may experience transient neurocognitive effects when moving their heads, research demonstrates.

Study participants who completed standardized head movements while inside the stray static magnetic field of a 7 Tesla (T) MRI system experienced a temporary decrease in attention, concentration, and visuospatial orientation that did not occur in sham conditions.

The findings add to evidence that MRI static fields - which are present once the machine is switched on even when imaging is not underway - can cause sensory symptoms such as nausea, dizziness, and a metallic taste in the mouth.

Discussing the impact of such side effects on MRI technicians, cleaners, and surgeons, lead author Hans Kromhout (University of Utrecht, the Netherlands) told medwireNews: "We think that given the (increasing) interactive use of MRI scanners (eg, brain surgery in the direct vicinity of an MRI scanner) manufacturers and users should look into measures to lower the exposure in order to prevent neurocognitive and balance effects, as shown in our experimental studies, to happen."

As reported in Occupational and Environmental Medicine, the research was conducted in 31 healthy volunteers who were asked to complete assessments for six neurocognitive domains 30-180 seconds after using head movements to induce time-varying magnetic fields while exposed to sham (0 T), low (0.5 T), and high (1.0 T) static fields.

The team detected a significant relationship between increasing T exposure and participant attention, indicating a reduced working memory and a decrease in visuospatial perception. There was also a trend toward a decrease in verbal memory functioning in the story recall test.

"We are at the moment not sure what the biological mechanism is for the neurocognitive symptoms and the postural body sway," Kromhout said. "We expect that the most likely pathway will involve the vestibular system."

He added that, while research indicates so far that the neurocognitive effects of MRI static stray fields disappear once exposure ends, the team are also investigating the possibility of long-term effects in workers exposed at an MRI manufacturing plant.

"Given the statistical limitations we will have a hard time finding any significant association, but if it is there we can only find it in this population since workers in health care and research have so far only had exposure for a limited amount of time," Kromhout commented.

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