Developing magnetorelaxometry imaging for human applications.

<i>Objective.</i>Magnetic nanoparticles (MNPs) are a promising tool in biomedical applications such as cancer therapy and diagnosis, where localization and quantification of MNP distributions are often mandatory. This can be obtained by magnetorelaxometry imaging (MRXI).<i>Approach.</i>In this work, the capability of MRXI for quantitative imaging of MNP inside larger volumes such as a human head is investigated. We developed a human head phantom simulating a glioblastoma multiforme (GBM) tumor containing MNP for magnetic hyperthermia treatment. The sensitivity of our MRXI setup for detection of MNP concentrations in the range of 3-19 mg cm^-3was studied.<i>Main result.</i>The results show the high capability of MRXI to detect MNPs in a human head sized volume. Superficial sources with a concentration larger than 12 mg cm^-3could be reconstructed with a resulotion of about 1 cm^-3.<i>Significance.</i>The reconstruction of the MNP distribution, mimicking a GBM tumor of 7 cm³volume with clinically relevant iron concentration, demonstrates the<i>in vivo</i>feasibility of MRXI in humans.