Abstract #3943

Reproducible B0 shim matrix calibration at 7T and dynamic range analysis of spherical harmonics for residual compensation

Istvan Homolya¹, Izabell Jaro², Yun Shang³, Grit Hein⁴, Matthias Gamer⁵, Martin Herrmann⁴, Laura Maria Schreiber¹, and Maxim Terekhov¹

¹Molecular and Cellular Imaging, Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany, ²Institute of Nuclear Techniques, Budapest University of Technology and Economics, Budapest, Hungary, ³Departments of Biomedical Engineering, Columbia University, New York, NY, United States, ⁴Department of Psychiatry, Psychosomatics, and Psychotherapy, University of Würzburg, Würzburg, Germany, ⁵Department of Psychology, University of Würzburg, Würzburg, Germany

Synopsis

Keywords: High-Field MRI, Shims

Motivation: Adequate B0 shimming of deep brain regions at 7T using 3^rd order shims.

Goal(s): Reproduce B0 shim matrix calibration after hardware replacement and estimate possible compensation of residual fields in vivo.

Approach: Calibration matrix of the 3^rd order B0 shimming system was measured after replacement of the gradient coil. Results were compared with previous calibration. Whole-brain and ROI-specific spherical harmonic decompositions of B0 maps were performed after optimized whole-brain shimming.

Results: Shimming calibration matrices could be reproduced with high accuracy on the new hardware. Residual B0 inhomogeneity could potentially be improved with existing shimming hardware.

Impact: B0 shimmming calibration matrix is well reproducible on a 7T system equipped with 3^rd order shim coils using single and multi-channel receiver coil configurations. Residual B0 inhomogeneity after optimized whole-brain shimming could be potentially improved using available shimming hardware.

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