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.