Magnetic manipulation in combination with preclinical magnetic particle imaging

Magnetic manipulation is of high interest in terms of drug targeting and minimal invasive surgery. Drugs as chemotherapeutics are bound to magnetic beads which can be directed by external magnetic fields towards a targeted volume. This allows lower dosages and healthy tissue is less affected. It is also possible to direct micro surgical devices, video or drug filled capsules into tissue regions which are difficult to access or into highly sensitive organs. It needs to be considered, how to image and monitor the manipulation process: For in-vitro experiments microscopy methods are possible, but in-vivo experiments need to be imaged with a tomographic and real time imaging technique – here, Magnetic Particle Imaging (MPI) is a promising method. MPI is an imaging modality determining the spatial distribution of superparamagnetic nanoparticles. It is highly sensitive and enables real time imaging with a resolution in the submillimeter range. It is based on the nonlinear response of the particles to alternating magnetic fields. A gradient field, forming a field free point (FFP), encodes the signal spatially. The magnetic fields of existing MPI scanners can also be used for magnetic manipulation. Since the magnetic force always points along the field gradient towards the highest field amplitudes, magnetic devices can be moved and rotated by moving the FFP, e.g. on circular path ways. The possible forces applied by a commercially available preclinical MPI system are investigated and the size of the devices movable by the available field gradients is determined. Since the administered force does not only depend on the size of the device and the magnetic field gradient, but also on the magnetization, it is aimed at analyzing the degree of magnetic saturation of the used devices and particles.