Design and simulation analysis on the magnetic field of matrix gradient coils for magnetic nanoparticle imaging system

Magnetic nanoparticle imaging (MNPI) is an emerging three-dimensional imaging technology, which has the advantages of high temporal resolution, high spatial resolution, and high sensitivity without the hazards of ionizing radiation. This technique has been utilized widely in medical imaging, biomarker and separation, drug delivery and therapy, especially in cardiovascular imaging. In MNPI system, the magnetic field (MF) generated by matrix gradient coils has prominent effect on the imaging resolution. To optimize the MF distribution and improve MNPI imaging resolution, in this paper, we built the matrix gradient coils simulation models, and the effects of the coil radius and spacing on the magnetic field distribution are comparatively analyzed by numerical simulation methods. Results found that the magnetic field gradient value gradually increases with decreasing coil size or spacing. While, homogeneity and stability of the magnetic field distribution will decrease with extreme coil size or spacing between two coils. The methods and conclusions in study can support the optimal design of matrix gradient coils in MNPI system and can potentially improve the resolution of MNPI.