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New equipment for tracking magnetic nanoparticles


At the Charité university hospital in Berlin on 12 June 2015, Prof. Dr. Johanna Wanka, Federal Minister of Education and Research, dedicated a magnetic particle imaging (MPI) device which is to be operated jointly by the Charité hospital and PTB. This device was funded with almost 4 million euros by the Deutsche Forschungsgemeinschaft (DFG) within the Major Equipment Initiative programme. With the MPI technology, it is possible to generate images of the distribution of magnetic nanoparticles in living tissue or in the blood flow with high temporal and spatial resolution.

Dedication of the MPI scanner on 12 June 2015 – from the left: L. Trahms (PTB), J. Wanka (Federal Minister of Education and Research), E. Braun (Philips), S. Krach (Secretary of State for Science, Berlin), M. Taupitz (Charité), J. Ullrich (PTB)

MPI was invented by the Philips company a few years ago. MPI is based on the signals of tracers: non-toxic iron oxide nanoparticles which are injected and are transported in the blood flow. Since these magnetic tracers react to an external magnetic field with a nonlinear response, they emit specific signals which the MPI device can detect in real time, with high sensitivity and high spatial resolution. This enables, for example, the observation of the blood flow as a film with a temporal resolution of only a few ms in order to investigate cardiovascular problems. PTB’s task is to provide a thorough metrological characterization of the iron oxide nanoparticles which are yet to be developed; this characterization is indispensable for an accurate quantitative interpretation of the MPI images. Various measurement procedures are used for this purpose: magnetic susceptometry, magnetic particle spectrometry as well as magnetic relaxometry – a procedure which was developed by PTB. In addition, numerical simulations are to be carried out on the basis of mathematical models and are subsequently to be compared with experimental investigations.