The present invention relates to an arrangement and a method for influencing and/or detecting magnetic particles in a region of action, in particular for monitoring of intra-cerebral or intra-cranial bleeding using Magnetic Particle Imaging (MPI). A common coupling unit per coil of a coil array is provided for coupling all signals for generating the magnetic fields to the set of common coils. Further, the same coils are used for acquiring detection signals. In this way a small scanner can be built that can be left permanently or can be provided periodically to the patient, in particular for bleeding monitoring.