Simulation of Remote Forces Generated by High-Temperature Superconducting Bulks for Magnetic Drug Delivery

The strong background fields and field gradients required for the magnetic delivery of chemotherapeutic drugs in cancer treatments has proven to be challenging to achieve at the scale of the human body. Although several magnetic drug delivery (MDD) methods have been proposed to generate adequate forces in deep tissues, current technologies lack in either force strength, directional changes, and/or duty cycle of the treatment. The current MDD system is capable of generating the strongest forces, dipole field navigation, uses ferromagnetic (FM) cores in the strong uniform field of an MRI to steer the drug-loaded particles. Hence, considering the nearly ten-fold increase in magnetization of high-temperature superconducting (HTS) bulks in comparison to the strongest FM, the forces obtained in dipole field navigation could potentially be increased by replacing the FM cores with HTS bulks. In this work, we evaluate two different methods for generating magnetic forces using an HTS bulk in a magnetic resonance imaging (MRI) scanner by using finite element method simulations. First, the HTS pellet is zero field cooled and inserted in the uniform field of an MRI, such that the pellet is magnetized by the fringe field of the MRI. Second, a field cooled HTS pellet is rotated in the uniform field of an MRI in order to generate magnetic field gradients. The magnetic forces produced by both methods are compared with those obtained by dipole field navigation. In both methods evaluated, we found that the forces generated by the HTS pellet are either complementary to or stronger than those obtained with FM cores. Therefore, this work shows that HTS bulks could potentially be used to navigate magnetic particles in the deep tissues of the human vascular network more efficiently.