Raiders of the lost SAR: Radiofrequency cycles of magnetic nanoflowers inside a tumor

Abstract

Radiofrequency magnetic cycles of ex vivo melanoma tumor tissue loaded with Fe3O4 nanoflowers (NF) were measured for several field conditions and compared with the cycles of a ferrogel (FG) obtained incorporating identical NF in agarose gel. Results were studied in order to understand a reported specific power dissipation (SAR) reduction of the NF in the actual application medium (tumor) in comparison with a typical characterization model as the FG. The linearity of the response, together with coercive field and SAR values were analyzed. Additionally, a novel method for the determination of the NF mean relaxation time is presented. Results show a systematic difference in magnetic response between the NF incorporated in the tumor and those in the FG for all field settings ({98, 170, 260} kHz and {17.4, 54.0} kA/m) with SAR reductions above 50%.