Magnetic-Particle-Imaging (MPI)

MPI Volkmar Schulz

Magnetic Particle Imaging (MPI) is a new tracer-based imaging technology, where a patient or an animal is injected with superparamagnetic iron oxide nanoparticles (SPIO). The SPIOs are excited by a dynamic external magnetic field and the non-linear response of the particles is recorded. The particle signal is closely proportional to their concentration. Spatial encoding of the particle distribution is achieved by superimposing a magnetic gradient field with three orthogonal fields which cancel out each other only at a single point in space (field-free point, FFP). All particles outside of the FFP are saturated and therefore do not contribute to the particle signal generated by periodically flipping the magnetization of the SPIOs. This method allows quantitative imaging of the tracer distribution inside the observed volume. The advantage of MPI over other imaging technologies is the very fast volume acquisition with more than 45 volumes per second at a sub-millimeter spatial resolution.

Our group works with the world’s first MPI scanner developed by Philips Research Hamburg as well as the world’s first commercial pre-clinical MPI scanner produced by Bruker BioSpin. The goal of our group is to improve the systems sensitivity, to enhance the understanding of the imaging process and to improve the reconstruction algorithms. Besides we are closely cooperating with pre-clinical users to enhance the existing imaging protocols and are therefore involved in biological studies.