Extending tuning coil loading for improved passive compensation in multi-frequency MPI towards nominal field strength operation

In Magnetic Particle Imaging (MPI), minimizing the feedthrough of the excitation signal into the receive signal helps in capturing the fundamental frequency response of the superparamagnetic iron oxide nanoparticle (SPIONs), improving the signal to noise ratio and assisting quantitative measurements. The concept of tuning coils can improve the performance of gradiometer receive coils by inducing suitable signals into the receive coils to reduce the remaining excitation signal without hampering the reception of the particle signal. Adjusting the current in the tuning coils is done by applying loading, controlled via solid state switches. In this work, an arrangement capable for operation at nominal field strength of a multi-frequency MPI (mf-MPI) scanner for mouse sized objects is presented. A high voltage loading board is applied. The adjustment of the load is integrated into an automated control loop.