Advancements in Magnetic Nanoparticle Reconstruction Using Sequential Activation of Excitation Coil Arrays Using Magnetorelaxometry

Magnetic nanoparticles can be employed for a broad range of biomedical applications where the knowledge of the distribution of the magnetic nanoparticles is of importance for efficacy, patient´s safety, etc. The need exists to have an as accurate as possible quantification of the unknown particles distribution. Magnetorelaxometry (MRX) measurements are able to measure the magnetic induction originating from a certain distribution of magnetically activated nanoparticles. Starting from these measurements it is possible to determine the distribution using a minimum norm estimation technique. This approach is however ill-posed. We sequentially activate the magnetic nanoparticles through the use of excitation coil arrays with the aim to reduce the ill-posedness. This paper presents some advancements in magnetic nanoparticle reconstruction in terms of reconstruction quality using numerical simulations. The results show that inhomogeneous sequential activation is a proper alternative to homogeneous activation with Helmholtz coils since an increase in accuracy with a factor ranging from 1.5 until 2 is obtained. The presented numerical techniques coupled to MRX measurements can be of significant aid so to have more quantitative knowledge of the biodistribution.