A Spectrometer for Magnetic Particle Imaging

Recently, a new tomographic imaging technique called magnetic particle imaging was proposed. It allows for the high resolution measurement of the spatial distribution of magnetic nanoparticles. The method is based on the non-linear response of magnetic nanoparticles (e.g. superparamagnetic iron oxide particles, SPIOs). In this work, a spectrometer is presented that allows for the analysis of the nanoparticle quality used in the imaging process. The number of useable harmonics in the non-linear particle response strongly depends on the diameter of the SPIOs. We have found that different lots do not perform equally. Therefore, improvements of the magnetic nanoparticles are desired. Since the instrument directly measures the non-linear characteristics of the nanoparticles, related properties for magnetic particle imaging can be achieved as well. This especially assists the chemical nanoparticle preparation process. An optimized coil setup to measure the particle response is described. Moreover, a series of measurements have been carried out to evaluate the spectral results using different field parameters and particle concentrations of commercially available MRI-approved SPIOs. Furthermore, the measurements are compared to simulations based on the Langivin theory of paramagnetism.