Purpose A temporary endovascular magnetic filter was developed to remove iron oxide particles conjugated to chemotherapeutics from the blood, preventing chemotherapeutics from circulating where it is not needed to reduce systemic toxicity and enable higher dose therapy. Magnetically targeted drug delivery through filtration could play an important role in expanding intra-arterial therapy to head and neck cancer. Previous proof-of-concept established rapid high-capacity binding of iron oxide particles in swine serum in vitro, and preliminary demonstration of qualitative efficacy in vivo in a porcine model. In this study, we aim to optimize the filtration efficacy of the prototype through finite element magnetic modeling.
Method Magnetic modeling was performed in 2D using Finite Element Method Magnetics (FEMM) software (Brighton, MA). Prototype designs consisting of individual neodymium N52 magnets were simulated to optimize the following parameters: i) magnetization across length vs diameter, ii) magnet orientations aligned or reversed, iii) magnet spacing, and iv) magnet length. The average magnetic flux gradient (∇By) was computed across a unit length consisting of one magnet and adjoining gap space as shown in Figure 1A. ∇By is directly correlated to the magnetic force on an iron particle, and was plotted as against D, distance from the surface of the magnet. Designs with greater ∇By at high D were considered more effective.
Results Designs with magnetization across the length and reversed (like polarities facing and repelling each other), had slightly higher ∇By than designs with magnetization across the diameter and aligned (opposite polarities facing and attracting each other). Magnetization across the length and aligned, and magnetization across the diameter and reversed both had low ∇By at high D. For designs with magnetization across the length and reversed orientations as shown in Figure 1B, reduced spacing between magnets increased ∇By. Reduced magnet length increased ∇By at low D, at the expense of ∇By at high D.
Conclusions The current endovascular magnetic filter prototype could be improved by using longer magnets magnetized across the length in the reversed orientation with like polarities repelling each other and minimal spacing between magnets.
Disclosures C. Sze: 1; C; NIH NCI. 5; C; ChemoFilter. M. Mabray: None. P. Lillaney: None. S. Kondapavulur: None. D. Liu: None. M. Wilson: 1; C; NIH NCI. 6; C; Penumbra. S. Hetts: 1; C; NIH NCI. 6; C; Penumbra.
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