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

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.