Design of a segmented RF shield to minimize eddy currents on low-field Halbach MRI systems

Motivation: Eddy-currents induced in the shielding layer placed between the gradient coils and RF transmit coil can create artefacts and lead to longer echo times. Reducing these currents by segmenting the shield while keeping the noise-reduction properties is important for low-field point-of-care systems. Goal(s): Minimizing eddy currents for transverse B0 magnets while maintaining shielding effectiveness. Approach: The segmentation locations are chosen by taking into account the wire pattern of the RF coil and gradient-induced eddy current simulations. Results: The suggested shield results in a decrease in the measured eddy current effects by a factor of 15, with only a noise increase of 4%. Impact: The proposed shield reduces eddy current effects by a factor of 15, giving the opportunity to achieve shorter echo-times and higher slew rates with fewer distortions on point-of-care low-field systems.