Premium
Simultaneous electroencephalography‐functional MRI at 3 T: An analysis of safety risks imposed by performing anatomical reference scans with the EEG equipment in place
Author(s) -
Nöth Ulrike,
Laufs Helmut,
Stoermer Robert,
Deichmann Ralf
Publication year - 2012
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.22843
Subject(s) - specific absorption rate , electroencephalography , magnetic resonance imaging , electromagnetic coil , biomedical engineering , computer science , nuclear medicine , nuclear magnetic resonance , materials science , physics , medicine , radiology , telecommunications , quantum mechanics , psychiatry , antenna (radio)
Purpose: To describe heating effects to be expected in simultaneous electroencephalography (EEG) and magnetic resonance imaging (MRI) when deviating from the EEG manufacturer's instructions; to test which anatomical MRI sequences have a sufficiently low specific absorption rate (SAR) to be performed with the EEG equipment in place; and to suggest precautions to reduce the risk of heating. Materials and Methods: Heating was determined in vivo below eight EEG electrodes, using both head and body coil transmission and sequences covering the whole range of SAR values. Results: Head transmit coil: temperature increases were below 2.2°C for low SAR sequences, but reached 4.6°C (one subject, clavicle) for high SAR sequences; the equilibrium temperature T eq remained below 39°C. Body transmit coil: temperature increases were higher and more frequent over subjects and electrodes, with values below 2.6°C for low SAR sequences, reaching 6.9°C for high SAR sequences (T8 electrode) with T eq exceeding a critical level of 40°C. Conclusion: Anatomical imaging should be based on T1‐weighted sequences (FLASH, MPRAGE, MDEFT) with an SAR below values for functional MRI sequences based on gradient echo planar imaging. Anatomical sequences with a high SAR can pose a significant risk, which is reduced by using head coil transmission. J. Magn. Reson. Imaging 2012;35:561‐571. © 2011 Wiley Periodicals, Inc.