Evaluation of Complex Harmonic Signals From Magnetic Nanoparticles for Magnetic Particle Imaging

Yonetani, Takashi; Tsujimura, Naotaka; Tanabe, K.; Sasayama, Teruyoshi; Enpuku, Keiji

doi:10.1109/tmag.2015.2441750

Cited by 6 publications

(4 citation statements)

References 18 publications

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“…Therefore, it is necessary to take account of the core size distribution when we use these MNPs samples for MNPT. Although we have shown that the numerical simulation including the core size distribution can quantitatively explain the static and dynamic magnetizations of MNPs sample, 13,14) numerical simulation took a lot of time. Since the 1st, 3rd, and 5th harmonic magnetization signals (M 1 , M 3 , and M 5 ) are used in MNPT, it is very useful if simple empirical expressions for these harmonic signals are obtained.…”

Section: Introductionmentioning

confidence: 98%

Empirical expression for harmonics of AC magnetization of magnetic nanoparticles with core size distribution

Sun

Higashi

et al. 2019

Jpn. J. Appl. Phys.

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It is well known that the core size of practical magnetic nanoparticle (MNP) samples is widely distributed. This study investigated an empirical expression for harmonics of AC magnetization of MNPs for magnetic nanoparticle thermometer (MNPT) and used two main core diameters to approximate the effect of the core size distribution. When the frequency of AC magnetic field was 200 Hz, the harmonics calculated from the Langevin function with two-core diameters (two-core-diameters model) agreed well with the experimental data. When the frequency was 3 kHz, where the effect of the Brownian relaxation could not be ignored, the harmonics could also be empirically expressed by the two-core-diameters model by adequately choosing the parameters of the model. The simple two-core-diameters model is useful when MNPs sample with core size distribution is used for MNPT.

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Section: Introductionmentioning

confidence: 98%

Empirical expression for harmonics of AC magnetization of magnetic nanoparticles with core size distribution

Sun

Higashi

et al. 2019

Jpn. J. Appl. Phys.

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“…In vivo cancer imaging using MPI has been reported with characteristic spatial resolution of approximately 1 mm 3) . The MPI signal is strongly dependent on the size or structure of the used particle 4,5) , so the resolution of MPI can be improved by optimizing these parameters. To achieve high spatial and temporal resolution of MPI, the magnetic properties of MNPs should be investigated, and optimal conditions related to the applied field and the MNP parameters should be determined.…”

Section: Introductionmentioning

confidence: 99%

“…As magnetic properties certainly depend on the core size of MNPs 4) , the effect of core size distribution was also studied with using the oriented MNPs.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Hysteresis Measurement of Magnetic Nanoparticles with Aligned Easy Axes

et al. 2018

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Magnetic particle imaging (MPI) is a novel diagnostic imaging technique based on the use of magnetic nanoparticles (MNPs). Investigating the magnetic properties of magnetic nanoparticles is important for achieving a high spatial and temporal resolution in MPI. In this study, -Fe2O3 nanoparticles (core diameter: dc = 4 nm), Fe3O4 nanoparticles (dc = 20-30 nm), and Resovist ® were immobilized in a DC magnetic field with their easy axes aligned. DC and AC magnetization curves were measured for the prepared MNPs. The measurements were performed by applying fields parallel and perpendicular to the easy axis and evaluating the magnetic properties of the MNPs for the easy and hard axes. The direction of magnetic moments under the AC magnetic field applied to the direction of the easy axis or hard axis was evaluated by using both experimental results and numeric simulation using the Landau-Lifshitz-Gilbert equation to reveal magnetic relaxation property at wide frequency range and the effect of core size distribution of oriented MNPs. The effect of anisotropy in superparamagnetic nanoparticles, the relaxation property depending on the anisotropy energy barrier, and the fast magnetization process of Néel relaxation were successfully observed.

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“…The measurements were performed using a measurement system developed at Kyushu University. 29) Symbols and lines represent the results obtained for η 1 = 0.917 mPa • s (water) and η 2 = 13.4 mPa • s (mixture of water and 60% glycerol), respectively. The results for μ 0 H ac = 6 and 20 mT are shown, where μ 0 is the permeability of the vacuum.…”

mentioning

confidence: 99%

Effect of core size distribution on magnetic nanoparticle harmonics for thermometry

Sun

Higashi

et al. 2019

Jpn. J. Appl. Phys.

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We investigated the effect of core size distribution on the performance of a magnetic nanoparticle thermometer (MNPT) in circumstances when Néel relaxation dominates the dynamic behavior of particles. Numerical simulations revealed the effects of excitation field strength and core size distribution on the temperature dependence of the amplitude and phase of harmonics. In MNPT, the field dependences of sensitivity deviated significantly from those calculated when the core size distribution was neglected. These simulation results were compared with those from experiments for which reasonable agreement was obtained. These findings must be carefully considered when designing an optimal MNPT system.

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Evaluation of Complex Harmonic Signals From Magnetic Nanoparticles for Magnetic Particle Imaging

Cited by 6 publications

References 18 publications

Empirical expression for harmonics of AC magnetization of magnetic nanoparticles with core size distribution

Empirical expression for harmonics of AC magnetization of magnetic nanoparticles with core size distribution

Dynamic Hysteresis Measurement of Magnetic Nanoparticles with Aligned Easy Axes

Effect of core size distribution on magnetic nanoparticle harmonics for thermometry

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