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Abstract #0142

Measurement and Pre-Emphasis of Shim Responses Using Frequency Sweeps

SUMMA25Signe Johanna Vannesjo1, Benjamin Dietrich1, Christoph Barmet1, Bertram J. Wilm1, David O. Brunner1, Klaas P. Pruessmann1

1Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland

Dynamic use of higher-order shims to improve static B0, puts increasing demands on characterization of shim field dynamics and requires pre-emphasis implementations to counteract eddy current effects. Measurements of the shim impulse response function (SIRF), using a dynamic field camera, and rectangular test functions, have previously been shown to provide detailed information on shim responses. Here, frequency-sweeped test pulses are implemented for wide bandwidth coverage and increased sensitivity of the SIRF measurements. It is shown that SIRFs thus measured could form a basis for digital pre-emphasis, enabling a flat frequency response and fast shim settling after a switching event.