Keywords: Gradients, High-Field MRI
Motivation: High-performance gradient coils can induce substantial eddy current in the magnet causing heating and artifacts. Motional eddy current at high B0 exacerbates the problem.
Goal(s): To investigate the feasibility of patterned, additional passive shielding to reduce both electromagnetically-indued and motional eddy currents.
Approach: A proof-of-concept experiment was conducted in flat geometry, where shielding efficiency at 3T was compared between a solid copper and a patterned copper plate that mimicked the eddy current image of a driving coil.
Results: The leakage field of patterned copper agreed with theory and was more localized in frequency and space. The shielding efficiency was improved at high frequencies.
Impact: We demonstrated that vibration-induced motional eddy current of a passive conductive shield can be dramatically altered by eddy current cut-outs. The results can be used to build a compact, high-field scanners with reduced magnet-gradient interaction.
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