TY  - JOUR
A1  - Schlamann, Marc
A1  - Voigt, Melanie A.
A1  - Maderwald, Stefan
A1  - Bitz, Andreas
A1  - Kraff, Oliver
A1  - Ladd, Susanne C.
A1  - Ladd, Mark E.
A1  - Forsting, Michael
A1  - Wilhelm, Hans
T1  - Exposure to high-field MRI does not affect cognitive function
JF  - Journal of Magnetic Resonance Imaging
N2  - Purpose
To assess potential cognitive deficits under the influence of static magnetic fields at various field strengths some studies already exist. These studies were not focused on attention as the most vulnerable cognitive function. Additionally, mostly no magnetic resonance imaging (MRI) sequences were performed.

Materials and Methods
In all, 25 right-handed men were enrolled in this study. All subjects underwent one MRI examination of 63 minutes at 1.5 T and one at 7 T within an interval of 10 to 30 days. The order of the examinations was randomized. Subjects were referred to six standardized neuropsychological tests strictly focused on attention immediately before and after each MRI examination. Differences in neuropsychological variables between the timepoints before and after each MRI examination were assessed and P-values were calculated

Results
Only six subtests revealed significant differences between pre- and post-MRI. In these tests the subjects achieved better results in post-MRI testing than in pre-MRI testing (P = 0.013–0.032). The other tests revealed no significant results.

Conclusion
The improvement in post-MRI testing is only explicable as a result of learning effects. MRI examinations, even in ultrahigh-field scanners, do not seem to have any persisting influence on the attention networks of human cognition immediately after exposure.
Y1  - 2010
U6  - http://dx.doi.org/10.1002/jmri.22065
SN  - 1522-2586
VL  - 31
IS  - 5
SP  - 1061
EP  - 1066
PB  - Wiley-Liss
CY  - New York
ER  - 
TY  - JOUR
A1  - Orzada, Stephan
A1  - Maderwald, Stefan
A1  - Poser, Benedikt Andreas
A1  - Bitz, Andreas
A1  - Quick, Harald H.
A1  - Ladd, Mark E.
T1  - RF excitation using time interleaved acquisition of modes (TIAMO) to address B1 inhomogeneity in high-field MRI
JF  - Magnetic Resonance in Medicine
N2  - As the field strength and, therefore, the operational frequency in MRI is increased, the wavelength approaches the size of the human head/body, resulting in wave effects, which cause signal decreases and dropouts. Several multichannel approaches have been proposed to try to tackle these problems, including RF shimming, where each element in an array is driven by its own amplifier and modulated with a certain (constant) amplitude and phase relative to the other elements, and Transmit SENSE, where spatially tailored RF pulses are used. In this article, a relatively inexpensive and easy to use imaging scheme for 7 Tesla imaging is proposed to mitigate signal voids due to B1 field inhomogeneity. Two time-interleaved images are acquired using a different excitation mode for each. By forming virtual receive elements, both images are reconstructed together using GRAPPA to achieve a more homogeneous image, with only small SNR and SAR penalty in head and body imaging at 7 Tesla.
Y1  - 2010
U6  - http://dx.doi.org/10.1002/mrm.22527
SN  - 1522-2594
VL  - 64
IS  - 2
SP  - 327
EP  - 333
PB  - Wiley-Liss
CY  - New York
ER  -