Localization and Actuation for MNPs Based on Magnetic Field-Free Point: Feasibility of Movable Electromagnetic Actuations.

Chan Kim,Chang-Sei Kim,Eunpyo Choi,Jayoung Kim,Jong-Oh Park

doi:10.3390/mi11111020

Abstract

Targeted drug delivery (TDD) based on magnetic nanoparticles (MNPs) and external magnetic actuation is a promising drug delivery technology compared to conventional treatments usually utilized in cancer therapy. However, the implementation of a TDD system at a clinical site based on considerations for the actual size of the human body requires a simplified structure capable of both external actuation and localization. To address these requirements, we propose a novel approach to localize drug carriers containing MNPs by manipulating the field-free point (FFP) mechanism in the principal magnetic field. To this end, we devise a versatile electromagnetic actuation (EMA) system for FFP generation based on four coils affixed to a movable frame. By the Biot–Savart law, the FFP can be manipulated by appropriately controlling the gradient field strength at the target area using the EMA system. Further, weighted-norm solutions are utilized to correct the positions of FFP to improve the accuracy of FFP displacement in the region of interest (ROI). As MNPs, ferrofluid is used to experiment with 2D and 3D localizations in a blocked phantom placed in the designed ROI. The resultant root mean square error of the localizations is observed to be approximately 1.4 mm in the 2D case and 1.6 mm in the 3D case. Further, the proposed movable EMA is verified to be capable of simultaneously scanning multiple points as well as the actuation and imaging of MNPs. Based on the success of the experiments in this study, further research is intended to be conducted in scale-up system development to design precise TDD systems at clinical sites.

Highlights

Targeted drug delivery (TDD) is considered to be a competitive solution to the treatment requirements for cancerous tumors
Based on the aforementioned imaging qualification criterion introduced in previous research, most magnetic particle imaging (MPI) systems require more than six electromagnets to generate 3D field-free point (FFP) with appropriate gradient fields for spatial imaging of Magnetic nanoparticles (MNPs)
MNPs are injected into the target area of another bifurcation phantom of similar size in accordance with the assumption

Summary

Introduction

Targeted drug delivery (TDD) is considered to be a competitive solution to the treatment requirements for cancerous tumors. Scaled-up variants of such systems meant for clinical applications require a large amount of space for the MPI equipment, such as the MPI scanner [27], and require further refinement In this context, we propose a novel approach for the actuation and imaging of MNPs in 3D regions of interest (ROIs) with the goal of developing a precise drug delivery system. Compared to the conventional MNP-steering approaches based on MPI scanners introduced in [26,27], the proposed architecture enables the implementation of magnetic tracers using fewer coils, making it a more efficient actuation method in TDD systems. The proposed method has the potential of practical clinical implementation due to its minimal installation space and easy access to patients during the procedure

System Description

FFP Generation

Prototyping

Discussions and Conclusions