Thresholds for perceiving metallic taste at high magnetic field

Purpose To perform an initial characterization of the metallic taste effect observed by some workers when moving around an MRI scanner. Materials and Methods A total of 21 subjects performed controlled movements in the stray field of a 7‐T scanner. Rates of change of magnetic flux were recorded during the study using a custom‐built three‐axis coil unit connected to a data logger. Results Relatively normal movements could generate switched fields of 2 T/second. Of the 21 subjects, 12 detected a metallic taste, but the threshold at which it was perceived varied greatly between subjects, with the minimum dB/dt value at which such a taste was detected being 1.3 T/second. The threshold also depended on the direction of movement. Conclusion This study indicates that 50% of subjects will perceive a metallic taste for head shaking with a period of 1.5 seconds (magnetic field in an anterior/posterior direction) causing a dB/dt of 2.3 ± 0.3 T/second. The presence of dental fillings is not a requirement for the sensation of metallic taste. J. Magn. Reson. Imaging 2007;26:1357–1361. © 2007 Wiley‐Liss, Inc.