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  -