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Abstract #4516

Correction of Parallel Transmit RF Pulses at 9.4 T Using Measured Gradient Waveforms

Xiaoping Wu1, J. Thomas Vaughan1, Kmil Ugurbil1, Pierre-Franois Van de Moortele1

1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA

Parallel Transmission (PT) allows for applying accelerated multidimensional spatially selective RF pulses through independent Transmit (Tx) RF channels, a feature especially promising at very high magnetic fields to compensate for B1 field inhomogeneity. However, gradient waveform distortions due to gradient system imperfections and/or eddy current can result in very poor excitation profiles. It has been shown that such degradation of excitation patterns can be effectively reduced by using measured k-space trajectories for RF pulse design. In the present work, we conducted PT experiments on a 9.4 T human scanner and measured k-space trajectories to calculate corrected RF pulses, resulting in dramatic excitation accuracy improvement.