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

Magnetic particle imaging (MPI), an emerging molecular imaging technique with high sensitivity and spatial resolution, requires effective suppression of background interference. A common practice is to first measure the background and subtract it from subsequent MNPs signal acquisition. However, frequent background measurements not only reduce imaging efficiency but can also introduce additional noise and repositioning artifacts. To address these limitations, we propose a background-free reconstruction method to eliminate dedicated background measurements. Specifically, a pair of differential symmetric offset fields is sequentially applied to excitation field, and the differential signal between the two acquisitions yields a pure MNPs response. Simulation results demonstrate that the approach significantly enhances imaging quality compared to background measurement method.