Tomografische Bildgebung der Temperatur mit magnetischen Nanopartikeln

Magnetic Particle Imaging (MPI) is a tracer-based imaging modality with great potential in medical diagnostics and therapy. It can expand the spectrum of existing imaging procedures such as magnetic resonance imaging (MRT) or computer tomography (Computer-Tomographie (CT)). In addition, with its low limit of detection for magnetic material, millimetre resolution and potential real-time capability, it also offers the possibility of replacing or at least reducing the use of existing systems based on radioactive markers, such as single-photon-emission-computer-tomography (SPECT) and positron emission tomography (PET). Two other promising methods based on MPI are hyperthermia for the generation of localised fever and targeted drug delivery (TDD). For both processes, knowledge of the temperature of the particles and the environment is of great importance, as recent publications in the research field of magnetic nanoparticles (MNP) show.
This work concerns the tomographic imaging of the temperature of MNP. The aim is to simultaneously measure the concentration-distribution and the temperature of the MNP using a single harmonic of the induction signal. The temperature is determined on the basis of the phase shift of the MNP under the influence of temperature. In addition, the system should be kept technically simple in order to minimise the hardware development effort. A single-harmonic-based narrow-band MPI-system (nbMPI) is constructed for this purpose.
The thesis first describes the concept of the system and then reports the construction process, which was based on an existing MPI scanner. The characterisation of suitable MNPs for the system is also part of this work. The commissioning of the MPI system has demonstrated that a resolution in the submillimetre range and a limit of detection in the order of a few hundred nanograms can be achieved.
Experiments on line and dot phantoms have been carried out to demonstrate the potential of the temperature determination based on the phase change of the MNP. It has been shown that the method is suitable for temperature estimation.