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Abstract #3483

L0-norm-Based Passive Shimming for Co-optimizing Magnetic Field Uniformity and Spherical Harmonic Characteristics

Wenchen Wang1, Yaohui Wang2, Riyu Wei3, Ewald Weber1, and Feng Liu1
1University of Queensland, Brisbane, Australia, 2Institute of Electrical Engineering, CAS, Beijing, China, 3Magnetica Ltd, Brisbane, Australia

Synopsis

Keywords: Magnets (B0), Magnets (B0)

Motivation: Passive shimming (PS) involves an iterative procedure with low efficiency and accuracy.

Goal(s): Enhance PS efficacy by incorporating dual harmonic-field constraints while reducing shim tray adjustments.

Approach: An L0-norm approach co-optimizes field harmonics and shim tray usage, enhancing shimming efficacy.

Results: Validated on a 7 T magnet, the technique improved field homogeneity from 85.36 ppm to 5.25 ppm, kept high-order harmonics below 2 ppm, and reduced shim tray adjustments by over 60%.

Impact: The new method optimizes field uniformity and harmonics in each iteration with minimized shim operations, offering a novel PS design applicable to various MRI magnet systems.

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