An MPI-apparatus comprising a magnet system for generating a time-varying and position-dependent magnetic field and a detection system detecting signals from MPI contrast agents exposed to said magnetic field within a detection volume, said signals being suitable for reconstructing an image of the spatial and temporal distribution of said MPI contrast agents, is characterized in that the magnet system comprises an array with a plurality of permanent magnetic elements geometrically arranged in such a way that at least a part of the plurality of permanent magnetic elements are moved with sufficient speed in the vicinity of the detection volume to create the spatial and temporal magnetic field variations for inducing within the contrast agent the MPI signals recorded by the detection system. This avoids the high power requirements of current MPI scanners, while opening the way for higher spatial resolutions and variable scanning frequencies.