Short Term Effects of Magnetic Resonance Imaging on Excitability of the Motor Cortex at 1.5T and 7T

Schlamann, Marc; Yoon, Min-Suk; Maderwald, Stefan; Pietrzyk, Thomas; Bitz, Andreas K.; Gerwig, Marcus; Forsting, Michael; Ladd, Susanne C.; Ladd, Mark E.; Kastrup, Oliver

doi:10.1016/j.acra.2009.10.004

« Previous Next »Academic Radiology
Volume 17, Issue 3 , Pages 277-281, March 2010

Short Term Effects of Magnetic Resonance Imaging on Excitability of the Motor Cortex at 1.5T and 7T

Marc Schlamann, MD
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Hufelandstraße 55, 45122 Essen, Germany
- Address correspondence to: M.S.
Min-Suk Yoon, MD
- Department of Neurology, University Hospital Essen, Hufelandstraße 55, 45122 Essen, Germany
Stefan Maderwald, MSc
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany
Thomas Pietrzyk, Cand.med.
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Hufelandstraße 55, 45122 Essen, Germany
Andreas K. Bitz, MSc
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Hufelandstraße 55, 45122 Essen, Germany
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany
Marcus Gerwig, MD
- Department of Neurology, University Hospital Essen, Hufelandstraße 55, 45122 Essen, Germany
Michael Forsting, MD
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Hufelandstraße 55, 45122 Essen, Germany
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany
Susanne C. Ladd, MD, MSc
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Hufelandstraße 55, 45122 Essen, Germany
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany
Mark E. Ladd, MD
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Hufelandstraße 55, 45122 Essen, Germany
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany
Oliver Kastrup, MD
- Department of Neurology, University Hospital Essen, Hufelandstraße 55, 45122 Essen, Germany

Received 26 June 2009; accepted 5 October 2009. published online 28 December 2009.

Rationale and Objectives

The increasing spread of high-field and ultra-high-field magnetic resonance imaging (MRI) scanners has encouraged new discussion of the safety aspects of MRI. Few studies have been published on possible cognitive effects of MRI examinations. The aim of this study was to examine whether changes are measurable after MRI examinations at 1.5 and 7T by means of transcranial magnetic stimulation (TMS).

Materials and Methods

TMS was performed in 12 healthy, right-handed male volunteers. First the individual motor threshold was specified, and then the cortical silent period (SP) was measured. Subsequently, the volunteers were exposed to the 1.5-T MRI scanner for 63minutes using standard sequences. The MRI examination was immediately followed by another TMS session. Fifteen minutes later, TMS was repeated. Four weeks later, the complete setting was repeated using a 7-T scanner. Control conditions included lying in the 1.5-T scanner for 63minutes without scanning and lying in a separate room for 63minutes. TMS was performed in the same way in each case. For statistical analysis, Wilcoxon's rank test was performed.

Results

Immediately after MRI exposure, the SP was highly significantly prolonged in all 12 subjects at 1.5 and 7T. The motor threshold was significantly increased. Fifteen minutes after the examination, the measured value tended toward normal again. Control conditions revealed no significant differences.

Conclusion

MRI examinations lead to a transient and highly significant alteration in cortical excitability. This effect does not seem to depend on the strength of the static magnetic field.

Key Words: Transcranial magnetic stimulation, high field-MRI, biological effects