A detailed signal generation of the magnetization response of magnetic nanoparticles (MNPs) as a result of externally applied magnetic fields with flux densities of several millitesla is of high interest for biomedical applications such as magnetic resonance imaging or magnetic particle imaging (MPI). Although, MNPs are already frequently used as contrast agents or tracer materials, experimental data are rarely compared to model predictions because of distinct deviations. In this article, we use a customized Brownian-dominated CoFe 2 O 4 particle system to compare experimental magnetic particle spectroscopy data with Fokker−Planck simulations considering the Brownian relaxation. The influences of viscosity, size distribution, excitation frequency, and field amplitude are studied. We show that the effective magnetic moment and cluster sizes can be determined using a sample viscosity series. As introduced, such particle systems can serve as model systems to evaluate mathematical expressions and to study dependences on physical influencing factors. Investigations of defined MNP systems and detailed characterizations enable a wide field of improved diagnosis and therapy applications, for example, mobility MPI and magnetic hyperthermia.

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temperature-resolved magnetic particle imaging (Mpi) represents a promising tool for medical imaging applications. in this study an approach based on a single calibration measurement was applied for highlighting the potential of Mpi for monitoring of temperatures during thermal ablation of liver tumors. For this purpose, liver tissue and liver tumor phantoms embedding different superparamagnetic iron oxide nanoparticles (SPION) were prepared, locally heated up to 70 °C and recorded with Mpi. optimal temperature Mpi Spions and a corresponding linear model for temperature calculation were determined. the temporal and spatial temperature distributions were compared with infrared (IR) camera results yielding quantitative agreements with a mean absolute deviation of 1 °C despite mismatches in boundary areas.

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