Effect of particle size and structure on harmonic intensity of blood-pooling multi-core magnetic nanoparticles for magnetic particle imaging

Abstract

Magnetic particle imaging has been developed by the optimization of the tracer materials, excitation systems, and system functions for image reconstruction. Here, we prepared and studied magnetic nanoparticles with different core diameters, coated by carboxymethyl-diethylaminoethyl dextran as a blood-pooling agent. For comparison, measurements were also performed using Resovist^®, a widely used tracer agent. Transmission electron microscopy analysis of the prepared samples of nanoparticles revealed monodisperse single-core, chainlike aggregation, and multi-core structures. For optimizing the core size and structure of magnetic nanoparticles for use as imaging tracers, we evaluated the magnetization response to an applied field and harmonic intensity by measuring direct and alternating current hysteresis loops. To evaluate the dependence of the harmonic intensity on the core size and particle structures, large-magnetization particles were assembled using magnetic separation. The harmonic intensity depended not only on the core size but also on the particle structure. Diameters and distributions of single- and multi-core particles are important parameters. Solid and liquid samples of particles were studied for characterization of imaging of solid objects (such as tumors and organs) and liquids (such as blood).