Background-free reconstruction in magnetic particle imaging via differential offset fields

Magnetic particle imaging (MPI) is a promising molecular imaging technique that enables quantitative visualization of the distribution of magnetic nanoparticles (MNPs). Yet, background signal affects the accurate quantitative assessment of MNPs. To suppress background signal, a common practice is to initially measure the background and subtract it during subsequent MNPs signal acquisition. However, frequent background measurements not only reduce imaging efficiency but can also introduce additional noise and repositioning artifacts. Here, we propose a background-free reconstruction method to eliminate dedicated background measurement. Specifically, a pair of differential symmetric offset fields are sequentially applied to excitation field, and the differential signal between two acquisitions yields a pure MNPs response. Simulation results show that the approach significantly enhances imaging quality compared to background measurement.