TITLE:
Usefulness of Magnetic Particle Imaging for Monitoring the Effect of Magnetic Targeting
AUTHORS:
Tomomi Kuboyabu, Akiko Ohki, Natsuo Banura, Kenya Murase
KEYWORDS:
Magnetic Particle Imaging, Magnetic Targeting, Magnetic Nanoparticles, Tumor-Bearing Mice
JOURNAL NAME:
Open Journal of Medical Imaging,
Vol.6 No.2,
June
8,
2016
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 × 106 cells) were implanted into the backs of
eight-week-old male BALB/c mice. When the tumor volume reached approximately
100 mm3, 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.