Size-dependent MR relaxivities of magnetic nanoparticles

作者：Joos Alexander^*; Loewa Norbert; Wiekhorst Frank; Gleich Bernhard; Haase Axel

来源：Journal of Magnetism and Magnetic Materials, 2017, 427: 122-126.

DOI：10.1016/j.jmmm.2016.11.021

• Magnetic nanoparticles
• Quantitative imaging
• MR relaxometry
• Hydrodynamic fractionation
• Magnetic particle spectroscopy

Magnetic nanoparticles (MNPs) can be used as carriers for magnetic drug targeting and for stem cell tracking by magnetic resonance imaging (MRI). For these applications, it is crucial to quantitatively determine the spatial distribution of the MNP concentration, which can be approached by MRI relaxometry. Theoretical considerations and experiments have shown that R-2 relaxation rates are sensitive to the aggregation state of the particles, whereas R-2(*) is independent of aggregation state and therefore suited for MNP quantification if the condition of static dephasing is met. We present a new experimental approach to characterize an MNP system with respect to quantitative MRI based on hydrodynamic fractionation. The first results qualitatively confirm the outer sphere relaxation theory for small MNPs and show that the two commercial MRI contrast agents Resovist((R)) and Endorem((R)) should not be used for quantitative MRI because they do not fulfill the condition for static dephasing. Our approach could facilitate the choice of MNPs for quantitative MRI and help clarifying the relationship between size, magnetism and relaxivity of MNPs in the future.

• 出版日期2017-4-1
• 单位河北医科大学