Theodoros Samaras
The huge research effort on developing and characterizing magnetic nanoparticles (MNP) with optimal features for hyperthermia (HT) reflects on the extended literature published in this area in recent years. Despite this effort, clinical translation of MNP-HT has seen little progress. One of the limiting factors in clinical practice is the induction of eddy currents inside healthy tissues. These induced currents restrict the strength of the external, alternating magnetic fields which can be used, thus failing to activate MNP in the target (cancerous) tissues and failing to increase temperature to the desired treatment level. In fact, it can be shown with realistic computational human phantoms that large parts of the human trunk are unfavourable for the use of external coils as devices for triggering the energy release by MNP, due to the formation of hotspots at specific anatomical structures in healthy tissues. Apart from local transdermal cooling, other techniques have been proposed for mitigating the impact of eddy currents heating. Such techniques include the use of intermittent exposure to the magnetic field or the motion of the coil during the HT treatment session. Numerical simulations for MNP-HT in vitro, which have been validated by experimental measurements, have shown that these mitigation techniques carry a large potential, if translated to clinical practice.
