Usefulness of Magnetic Particle Imaging for Monitoring the Effect of Magnetic Targeting

Abstract

Purpose: Magnetic targeting refers to the attachment of therapeutic agents to magnetizable particles such as magnetic nanoparticles (MNPs) and then applying magnetic fields to concentrate them to the targeted region such as solid tumors. The purpose of this study was to investigate the usefulness of magnetic particle imaging (MPI) for monitoring the effect of magnetic targeting using tumor-bearing mice. Materials and Methods: Colon-26 cells (1 × 10 6 cells) were implanted into the backs of eight-week-old male BALB/c mice. When the tumor volume reached approximately 100 mm 3 , the mice were divided into treated (n = 8) and untreated groups (n = 8). The tumors in the treated group were directly injected with MNPs (Resovist ® , 250 mM) and a neodymium magnet was attached to the tumor surface, whereas the magnet was not attached to the tumor in the untreated group. The mice were imaged using our MPI scanner and the average and maximum MPI values were obtained by drawing a region of interest (ROI) on the tumor, with the threshold value for extracting the contour of the tumor being taken as 40% of the maximum MPI value in the ROI. The relative tumor volume growth (RTVG) was calculated from (V − V0)/V0, where V0 and V represented the tumor volume immediately before and after the injection of MNPs, respectively. Results: The average and maximum MPI values in the treated group were significantly higher than those in the untreated group 3 days after the injection of MNPs, suggesting the effectiveness of magnetic targeting. There were no significant differences in RTVG between the two groups. Conclusion: Our preliminary results suggest that MPI is useful for monitoring the effect of magnetic targeting.

Magnetic particle imaging: tracer development and the biomedical applications of a radiation-free, sensitive, and quantitative imaging modality

“…MPI is particularly useful because of the linear quantitation and lack of background signal, providing spatial information which allows the accurate monitoring of therapeutic agent delivery. 305 This information illustrates the quantity of drug delivered to the target site, as well as the drug dosage distribution within the body. The ability to track drug delivery also allows for real-time adjustment of ensuing doses, ensuring that the dosage at the target site remains within the patient's therapeutic window (Fig.…”

Simultaneous Magnetic Particle Imaging and Navigation of large superparamagnetic nanoparticles in bifurcation flow experiments

“…The ability to move particles with MPI for targeted drug delivery has also been presented. [13][14][15][16][17] Griese et al 18 have demonstrated how to simultaneously move and image micron-sized magnetic particles with the Magnetic Particle Imaging/Navigation (MPIN) method with a temporal arXiv:1906.07518v1 [physics.app-ph] 18 Jun 2019 resolution of 2.9 Hz. Micron-sized particles have been used to target endothelial cells of the central nervous system to identify over-expressed surface proteins such as ICAM-1.…”

Magnetic particle imaging for aerosol-based magnetic targeting

“…6) Magnetic targeting has been developed for localizing drug carriers such as liposomes containing both MNPs and therapeutic agents in the targeted organ or tissue by applying external magnetic fields. 7) The magnetic targeting of therapeutic agents results in the concentration of the agents at the targeted site, consequently reducing or eliminating systemic unwanted side effects. 7) Recently, a new magnetic targeting strategy called "aerosol-based magnetic targeting" has been introduced for lung diseases.…”

“…7) The magnetic targeting of therapeutic agents results in the concentration of the agents at the targeted site, consequently reducing or eliminating systemic unwanted side effects. 7) Recently, a new magnetic targeting strategy called "aerosol-based magnetic targeting" has been introduced for lung diseases. 8) Aerosol-based magnetic targeting uses magnetic aerosol droplets comprising nebulized MNPs and therapeutic agents.…”