Numerical design of transverse gradient coil with transformed magnetic gradient field over an effective imaging area

Gradient coil is an essential component of a magnetic resonance imaging (MRI) scanner. To achieve high spatial resolution and imaging speed, a high-efficiency gradient coil with high slew rate is required. In consideration of the safety and comfort of the patient, the mechanical stability, acoustic noise and peripheral nerve stimulation (PNS) are also need to be concerned for practical use. In our previous work, a high-efficiency whole-body gradient coil set with a hybrid cylindrical-planar structure has been presented, which offers significantly improved coil performances. In this work, we propose to design this transverse gradient coil system with transformed magnetic gradient fields. By shifting up the zero point of gradient fields, the designed new Y-gradient coil could provide enhanced electromagnetic performances. With more uniform coil winding arrangement, the net torque of the new coil is significantly reduced and the generated sound pressure level (SPL) is lower at most tested frequency bands. On the other hand, the new transverse gradient coil designed with rotated magnetic gradient fields produces considerably reduced electric field in the human body, which is important for the use of rapid MR sequences. It's demonstrated that a safer and patient-friendly design could be obtained by using transformed magnetic gradient fields, which is critical for practical use.