4th International Workshop on MPI, organized by Medisert and TSB, will take place on March 27-29, 2014 in Berlin, Germany. Particle Science, Imaging Technology, and Clinical Application Magnetic Particle Imaging (MPI) is a novel imaging modality which uses various static and oscillating magnetic fields, as well as tracer materials made from iron oxide nanoparticles to perform background-free measurements of the particles’ local concentration. The method exploits the non-linear re-magnetization behavior of the particles and has the potential to surpass current methods for the detection of iron oxide in sensitivity and spatio-temporal resolution. The workshop aims at covering the status and recent developments of both, the instrumentation and the tracer material, as each of them is equally important in designing a well performing MPI. Furthermore, the workshop aims at presenting first results from phantom and pre-clinical studies. The workshop will provide the opportunity to present your research and your results to a highly interested audience of professionals and academic experts active in the field of MPI.