Magnetic particle imaging (MPI) using the nonlinear interaction between internally administered magnetic nanoparticles
(MNPs) and electromagnetic waves irradiated from outside of the body has attracted attention for the early diagnosis of
diseases such as cancer. In MPI, the local magnetic field distribution is scanned, and the magnetization signal from
MNPs inside an object region is detected. However, the signal sensitivity and image resolution are degraded by
interference from the magnetization signal generated by MNPs that exist outside of the desired region, owing to
nonlinear responses. Earlier, we proposed an image reconstruction method for suppressing the interference component
while emphasizing the signal component using the property of the higher harmonic components generated by the MNPs.
However, edge areas in the reconstructed image were emphasized excessively owing to the high-pass-filter effect of this
method. Here, we propose a new method based on correlation information between the observed signal and a system
function. We performed a numerical analysis and found that, although the image was somewhat blurred, the detection
sensitivity can clearly be improved without the inverse-matrix operation used in conventional image reconstruction.