RF excitation using time interleaved acquisition of modes (TIAMO) to address B1 inhomogeneity in high-field MRI

  • 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.

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Metadaten
Author:Stephan Orzada, Stefan Maderwald, Benedikt Andreas Poser, Andreas Bitz, Harald H. Quick, Mark E. Ladd
DOI:https://doi.org/10.1002/mrm.22527
ISSN:1522-2594
Parent Title (English):Magnetic Resonance in Medicine
Publisher:Wiley-Liss
Place of publication:New York
Document Type:Article
Language:English
Year of Completion:2010
Volume:64
Issue:2
First Page:327
Last Page:333
Link:https://doi.org/10.1002/mrm.22527
Zugriffsart:campus
Institutes:FH Aachen / Fachbereich Elektrotechnik und Informationstechnik
collections:Verlag / Wiley-Liss