Design and application of a 16-channel field-probe insert for a 16Tx/32 Rx coil at 9.4 Tesla

Motivation: Gradient imperfections and significant field fluctuations due to physiology at higher field can degrade the image quality and thus limit the use of certain readout trajectories. Goal(s): To perform concurrent monitoring of the encoding gradients and other spatio-temporal field variations during imaging at 9.4 Tesla. Approach: We optimized, designed and manufactured a highly customizable field-probe insert for a 16Tx/32Rx RF array and performed an initial in-vivo experiment. Results: The locations of the probes yield good conditioning for measuring field up to second order spherical harmonics and showed an acceptable reduction in decay time. We demonstrated concurrent field monitoring with a 2D spiral experiment. Impact: Correction of trajectory and field deviations due to system imperfections and physiological effects is important for measurements with long readouts and echo times at ultra-high fields. We present a coil insert that allows simultaneous field monitoring at 9.4 T.