A Streamlined 3-D Magnetic Particle Imaging System With a Two-Stage Excitation Feed-Through Compensation Strategy

Magnetic particle imaging (MPI) is an innovative molecular imaging technique with remarkable sensitivity and temporal–spatial resolution. It employs superparamagnetic iron oxide nanoparticles (SPIONs) as tracers to precisely locate lesions in quantitative imaging. In practical, the induced signal of the receiver coil contains both the SPIONs magnetization signal and the excitation feed-through signal. Due to the high amplitude of the latter, extracting the SPIONs signal from the induced signal is a challenging task. In this study, a two-stage compensation strategy was proposed to suppress excitation feed-through signal. Firstly, we used a three-stage gradiometer coil to suppress part of the feed-through signal. Secondly, different from using the band-stop filters in most previous studies, we proposed a modulation compensation strategy that the received signal from the first stage and a modulation signal were input to the differential circuit at the same time, and the feed-through signal can be suppressed by actively adjusting the modulation signal. In addition, we presented a 3-D MPI system with a simple and effective structure. Permanent magnets were used to generate gradient fields, and the two-stage compensation strategy was employed at the receiving chain. Experimental results showed that the proposed compensation strategy can obviously suppress the excitation feed-through signal, which allows to achieve a high resolution and sensitivity imaging with the proposed 3-D MPI system.