MRI‐related static magnetic stray fields and postural body sway: A double‐blind randomized crossover study

Abstract

We assessed postural body sway performance after exposure to movement induced time-varying magnetic fields in the static magnetic stray field in front of a 7 Tesla (T) magnetic resonance imaging scanner. Using a double blind randomized crossover design, 30 healthy volunteers performed two balance tasks (i.e., standing with eyes closed and feet in parallel and then in tandem position) after standardized head movements in a sham, low exposure (on average 0.24 T static magnetic stray field and 0.49 T·s(-1) time-varying magnetic field) and high exposure condition (0.37 T and 0.70 T·s(-1)). Personal exposure to static magnetic stray fields and time-varying magnetic fields was measured with a personal dosimeter. Postural body sway was expressed in sway path, area, and velocity. Mixed-effects model regression analysis showed that postural body sway in the parallel task was negatively affected (P < 0.05) by exposure on all three measures. The tandem task revealed the same trend, but did not reach statistical significance. Further studies are needed to investigate the possibility of independent or synergetic effects of static magnetic stray field and time-varying magnetic field exposure. In addition, practical safety implications of these findings, e.g., for surgeons and others working near magnetic resonance imaging scanners need to be investigated.

Occupational exposure levels of static magnetic field during routine MRI examination in 3 T MR system

“…A stray field of several hundreds of mT remains around 3 T MRI system. Motion‐induced current in this area is known to cause temporal sensations such as vertigo, nausea, magnetophosphenes, and some changes in cognitive functions [Schenck, ; Chakeres and de Vocht, ; Crozier and Liu, ; de Vocht et al, and ; Glover et al, ; van Nierop et al, ]. Concerns regarding occupational exposure to SMFs have also become a recent focus in the published International Committee of Non‐Ionizing Protection (ICNIRP) Guidelines [ICNIRP, ; ICNIRP, ] and European Union (EU) Directive 2004/40/EC [EU Directive, ].…”

Exposure to static magnetic fields and risk of accidents among a cohort of workers from a medical imaging device manufacturing facility

“…While effects of acute MRI‐related EMF exposure have been studied in the manufacturing environments as well as in clinical settings , and among human volunteers , no studies have been published on the effects of long‐term occupational exposure to SMF. Our study is unique as it focusses on risk of accidents associated with both long‐term and recent exposure of workers in MRI‐systems manufacturing.…”

“…volunteers (1,3,4,6,17), no studies have been published on the effects of long-term occupational exposure to SMF. Our study is unique as it focusses on risk of accidents associated with both long-term and recent exposure of workers in MRI-systems manufacturing.…”

Transient health symptoms of MRI staff working with 1.5 and 3.0 Tesla scanners in the UK

“…Some of these reported effects may be related to adverse effects on visual perception, spatial orientation, visuomotor performance, working memory, and attention, measured in controlled trials [10][11][12][13]. Experimental studies similarly show that exposure to the static magnetic field has a direct negative, but temporary, effect on the vestibular system [14][15][16][17][18]. The effects seem stronger following (head) movements in the heterogeneous stray field, particularly near the outer edge of the magnet bore where the static field changes most rapidly in space, but are not observed with time-varying magnetic fields without the presence of a static gradient magnetic fields [19].…”