A Passive Copper Shield for the Split MRI System

Limei Liu¹, Hector Sanchez Lopez¹, Michael Poole¹, Ewald Weber¹, Feng Liu¹, Stuart Crozier¹

the eddy currents generated by the switching gradient fields produce undesired joule heating, noise and image artefacts in the MRI system. It is found that these eddy current effects are worsened in the split MRI system which is designed for the hybrid PET-MRI technology to provide high resolution images for the target tissues. In this work, a passive copper shield was applied outside of the split gradient coils to reduce the eddy currents induced in the cryostat inner bore in order to protect the contained helium vessel. The results show that the passive copper shield can effectively reduce the power heating in the cryostat inner bore. However, it sacrifices the gradient linearity in the region of interest.