Static magnetic field effects on human subjects related to magnetic resonance imaging systems.
OBJECTIVE
This paper reviews recent studies evaluating human subjects for physiologic or neuro-cognitive function adverse effects resulting from exposure to static magnetic fields of magnetic resonance imaging systems.


METHODS
The results of three studies are summarized. Two studies evaluated exposure to a maximum of 8 Tesla (T). The first series studied 25 normal human subjects' sequential vital signs (heart rate, blood pressure, blood oxygenation, core temperature, ECG, respiratory rate) measured at different magnetic field strengths to a maximum of 8 T. A second series of 25 subjects were studied at 0.05 and 8 T (out and in the bore of the magnet), performing 12 different standardized neuro-psychological tests and auditory-motor reaction times. The subjects' comments were recorded immediately following the study and after a three-month interval. The third study contained 17 subjects, placed near the bore of a 1.5 T magnet, and it used six different cognitive, cognitive-motor, or sensory tests.


RESULTS
There were no clinically significant changes in the subjects' physiologic measurements at 8 T. There was a slight increase in the systolic blood pressure with increasing magnetic field strength. There did not appear to be any adverse effect on the cognitive performance of the subjects at 8 T. A few subjects commented at the time of initial exposure on dizziness, metallic taste in the mouth, or discomfort related to the measurement instruments or the head coil. There were no adverse comments at 3 months. The 1.5 T study had two of the four neuro-behavioral domains exhibiting adverse effects (sensory and cognitive-motor).


CONCLUSIONS
These studies did not demonstrate any clinically relevant adverse effects on neuro-cognitive testing or vital sign changes. One short-term memory, one sensory, and one cognitive-motor test demonstrated adverse effects, but the significance is not clear.
Chakeres
Donald W
DW
Department of Radiology, College of Medicine and Public Health, Ohio State University Hospital, The Ohio State University, 630 Means Hall, 1654 Upham Drive, Columbus, OH 43210-1228, USA. chakeres-1@medctr.osu.edu
de Vocht
Frank
F
D001794:Blood Pressure / Q000528:radiation effects*; D004562:Electrocardiography / Q000528:radiation effects*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000009:adverse effects*; D008280:Magnetics / Q000009:adverse effects*; D009043:Motor Activity / Q000528:radiation effects*