Preparing system functions for quantitative MPI

Theoretically, Magnetic particle imaging (MPI) pledges quantitative imaging of magnetic nanoparticle (MNP) distributions. By an eight-shaped hosepipe phantom experiment using Ferucarbotran (Resovist precursor) as a tracer, we investigated the quantification capability of a commercial preclinical MPI-scanner (Bruker/Philips Preclinical MPI System, Germany) operated at Charite university hospital, Berlin. For reconstruction of MPI images of the MNP distribution we used a set of four system functions (SF) acquired with a tracer reference at different iron concentrations (in the range 0.1 mol/L to 1 mol/L). From the analysis of a selected region of interest in the reconstructed images, we found a linear relation between voxel values and the inverse of the concentration of the corresponding reference used in the particular SF acquisition. Based on the precisely known total tracer amount, we determined the tracer amount of each single voxel volume in the phantom from the MPI image. This could be achieved independent of the concentration of the reference used in the SF acquisition.