Localization of a magnetic nanoparticle spot from features of the magnetic field pattern and comparison to a magnetic dipole fit

摘要

Magnetic nanoparticles are increasingly used for biomedical applications such as magnetic drug targeting, magnetic hyperthermia or molecular imaging. These applications require novel methods to quantify non-invasively the magnetic nanoparticle uptake in different body organs. We used a multichannel magnetorelaxometry system based on superconducting quantum interference devices (SQUIDs) to measure specifically the magnetic field corresponding to a focal nanoparticle source. Analytical expressions are derived to estimate the source location and strength directly from the measured mag-netic field patterns for known magnetization direction. The results are compared to those of the established method of non-lincarly fitting the parameters of a magnetic dipole using a Levenberg-Marquardt algorithm.