Magnetic-Particle-Discrimination Method Using Difference of Relaxation Time for Magnetic Particle Imaging

Viscosity Effects on Relaxation Time Differences of Magnetic Nanoparticles

“…Fig. 2 present an overview and a diagram of our developed MPI system 8) . It employs a field-free line (FFL) method, which forms a zero-field region on a line by arranging opposing magnets that combine a U-shaped iron core with permanent magnets.…”

“…For example, relaxation time difference ∆𝜏 E between samples 1 and 2 can be calculated using Eq. ( 4) 8) :…”

“…One was Resovist (commercially distributed by FUJIFILM RI Pharma, Japan) and the other two were MNPs with core particle sizes of 25 nm (SA25) and 15 nm (SA15) (Sigma-Aldrich). The hydrodynamic particle sizes of SA25 and SA15 were 35.9 and 62.5 nm by dynamic light scattering (DLS) 8) . The core particle size and the hydrodynamic particle size of Resovist were obtained from T. Yoshida et al 9) Fig.…”

“…The core particle size and the hydrodynamic particle size of Resovist were obtained from T. Yoshida et al 9) Fig. 3 shows the DC susceptibility characteristics of each MNP 8) . In the range of AC field strengths used in this study, the DC magnetization of Resovist is the largest; that of SA25 is the smallest.…”

“…We developed an MPI system capable of detecting differences in the magnetic properties and relaxation times of MNPs in different media as signal-phase differences 8) . Arbitrary MNPs can be distinguished based on phase differences and only image arbitrary MNPs via signal processing.…”