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Abstract #4385

Towards Combined Brain and Cervical Spine Imaging at 7 T with an 8-channel pTx Coil: The Importance of Accurate B1+ Maps for Dynamic pTx

Christoph Stefan Aigner1,2, Markus W. May3,4, Thomas M. Fiedler5, Simone Kühn6, Harald H. Quick3,4, and Sebastian Schmitter2,5,7
1Max Planck Research Group MR Physics, Max Planck Institute for Human Development, Berlin, Germany, 2Physikalisch-Technische Bundesanstalt (PTB), Berlin, Germany, 3High-Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany, 4Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Essen, Germany, 5German Cancer Research Center (DKFZ), Heidelberg, Germany, 6Center for Environmental Neuroscience, Max Planck Institute for Human Development, Berlin, Germany, 7Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States

Synopsis

Keywords: High-Field MRI, Parallel Transmit & Multiband, 7 Tesla, parallel transmit (pTX), Brain and Spinal Cord, Universal Shim

Motivation: Current combined brain and cervical spine pTx coils at 7 Tesla require more than eight transmit (Tx) channels, limiting their widespread use.

Goal(s): To investigate wether a pTx coil with eight Tx elements and tailored and universal pTx achieves uniform flip-angles (FA) simulataneously across the brain and cervical spine regions.

Approach: Simulated B1+ maps were calculated for the Duke and Ella models. Tailored phase-only RF shims and dynamic kT-points pulses were optimized for FA homogeneity.

Results: Dynamic tailored/universal kT-points pulses significantly improved FA homogeneity over RF shimming (5/2.5x for 5-kT-points). Accurate B1+ information is crucial for optimal FA homogeneity in dynamic pTx.

Impact: This simulation study demonstrates feasability of combined brain and cervical spine MRI at 7 Tesla using an eight Tx channel dynamic pTx setup. Optimized pTx pulses result in high FA homogeneity and enable detailed investigations of both neuroanatomical structures simultaneously.

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Abstract

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