Effect of routine MR imaging of the brain at 1.5 T on subsequent magnetoencephalography: results in nine volunteers.
OBJECTIVE
To investigate whether routine magnetic resonance (MR) imaging of the brain with a whole-body 1.5-T imager affects the results of subsequent magnetoencephalography (MEG).


METHODS
Nine healthy volunteers (six women, mean age of 23 years, age range of 20-27 years; three men, mean age of 24 years, age range of 23-25 years) underwent one MEG session before and two MEG sessions after MR imaging of the brain. The first MEG session was completed about 20 minutes before brain MR imaging began, the second MEG session (MEG 2) was performed within 30 minutes after MR imaging, and the third MEG session was performed 2 hours after MEG 2. Each MEG session involved measurement of spontaneous brain activity and, in seven patients, of brain activity during stimulation of the median nerve. MR imaging included T1- and T2-weighted fast spin-echo and gradient-echo sequences applied with a 1.5-T clinical imager. Data were compared by using a repeated-measures analysis of variance (general linear model) both with and without Greenhouse-Geisser correction.


RESULTS
MEG signals were detected and measured without difficulty in all volunteers. No statistically significant difference was seen between estimated noise at MEG before and after MR imaging (P =.588 with correction, P =.665 without correction). MEG records obtained in all volunteers enabled localization of evoked response to median nerve stimulation before and after MR imaging. No measurable differences were observed between relative power spectra of spontaneous brain activity before and after MR imaging (P >.290 with correction, P >or=.295 without correction).


CONCLUSIONS
No measurable effect of 1.5-T brain MR imaging on subsequent MEG was detected.
Fitzek
Clemens
C
Institute of Diagnostic and Interventional Radiology/AB Neuroradiology MRI, Friedrich-Schiller-Universität Jena, Germany. clemens.fitzek@med.uni-jena.de
Haueisen
Jens
J
Huonker
Ralf
R
Reichenbach
Jürgen R
JR
Pfleiderer
Stefan O R
SO
Mentzel
Hans-Joachim
HJ
Sauner
Dieter
D
Brandl
Ulrich
U
Kaiser
Werner A
WA
D000328:Adult; D016477:Artifacts; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology / Q000528:radiation effects*; D004558:Electric Stimulation; D004574:Electromagnetic Fields / Q000009:adverse effects*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology / Q000528:radiation effects; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000009:adverse effects*; D015225:Magnetoencephalography / Q000528:radiation effects*; D008297:Male; D008475:Median Nerve / Q000502:physiology; D011446:Prospective Studies; D012016:Reference Values; D012815:Signal Processing, Computer-Assisted; D009435:Synaptic Transmission / Q000502:physiology / Q000528:radiation effects