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Abstract #0967

An integrated 32ch RF-shim array coil for improved B0 shimming of the brain at 7 Tesla

Jason Stockmann1,2, Thomas Witzel1,2, Nicolas Arango3, Azma Mareyam1, Charlotte Sappo1, Jiazheng Zhou4, Joshua Park1, Boris Keil1, Lucas Jenkins1, Markus May5, Jonathan R Polimeni1,6, Jacob White7, and Lawrence L Wald1,6

1A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, 2Harvard Medical School, Boston, MA, United States, 3Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, 4Institute of Biomedical Engineering, National Taiwan University, Taiwan, 5Electronic and Mechatronic Systems, Technische Hochschule Nürnberg, Nürnberg, Germany, 6Harvard Medical School, Boston, United States, 7Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, United States

Dual-purpose arrays of close-fitting coils, used to both receive RF and shim B0 to high spatial order, have recently been demonstrated in brain imaging at 3T. We extend this approach to 7T with an array comprised of: six RF coils, twenty-six RF/B0-shim coils, and six shim-only coils. The shim coils are driven by an array of low-cost current-feedback amplifiers that can steer up to fifty amps of shimming currents rapidly and accurately enough to allow for slice-by-slice adjustments. The resulting slice-optimal high-order shim capability (wires and chokes) improves σB0 in brain slices by up to 60% (as compared to static 2nd-order global shimming), while worsening SNR by less than 10%, and increasing coil coupling by less than 3%.

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