Manipulation of Magnetically Coated Swimmers Inside a Magnetic Particle Imaging Scanner

Magnetic manipulation of medical devices such as catheters, small cameras or drug filled capsules enables to improve the precision of minimally invasive surgery. Catheters can be steered towards tissue regions difficult to access. Drugs can be delivered directly to cancerous tissue or inflammatory regions, which allows lower dosages and healthy tissue is less affected. In-vitro experiments can be easily visualized with video and microscopy methods, but the manipulation process in-vivo needs to be imaged with a tomographic real-time imaging technique to facilitate image guided interventions. Here, Magnetic Particle Imaging (MPI) is a promising method. [1,2] MPI images the spatial distribution of superparamagnetic nanoparticles. It is based on the nonlinear response of the particles to alternating magnetic fields. A gradient field forming a field free point encodes the signal spatially. A commercially available preclinical MPI scanner (Bruker Biospin MPI 25/20 FF) features homogeneous offset fields, called focus fields, applicable in three dimensions to enlarge the field of view. [3]