USPIOs

The dispersion of this spectral density occurs about coiTd = 1- Its amplitude is always larger than the Freed component. This model matches the experimental relaxation results for large particles containing more than one crystal by coating flake (Small Particles of Iron Oxide, SPIO), but fails to describe the low field part of the NMRD curves of Ultra Small Particles of Iron Oxide (USPIO) containing only one magnetic crystal by particle (Fig. 6). 

Theoretical predictions are clearly different in the low field relaxation profiles observed for small particles (weak dispersion) and larger particles (no dispersion). These predictions are confirmed by the difference between the NMRD profiles of SPIO and USPIO particles. Further experimental... 

For USPIO particles containing only one nanomagnet per particle, the main parameters determining the relaxivity are the crystal radius, the specific magnetization and the anisotropy energy. Indeed, the high field dispersion is determined by the translational correlation time t. ... 

Ultra small particles of iron oxide (USPIO)... 

USPIO contrast agents are eliminated from the circulation by the reticuloendothelial system (RES), and often become sequestered in liver cells. Half-life in the circulation depends on the chemistry of preparation, and can range from... 

Most clinically used nanoparticle contrast agents are iron-oxide based and are grouped into two categories Superparamagnetic iron oxides (SPIOs) are between 500 nm and 50 nm, and ultra-small SPIOs (USPIOs), which are smaller than 50 nm. 

USPIOs can be used as blood pool agents because their smaller size allows them to remain in the bloodstream for longer times. They can be used... 

USPIO The ultrasmall iron oxide particles have good Tl relaxation properties, especially at lower fields (1.5 T). Their small size and coating enables them to evade the RES and remain in the blood pool they are too large to extravasate. The dextran-coated formulation NC100150 was evaluated in multicenter trials and found to be effective, but ultimately, it... 

Di Marco, M. Sadun, C. Port, M. Guilbert, I. Couvreur, P. Dubemet, C., Physicochemical characterization of ultrasmall superparamagnetic iron oxide particles (USPIO) for biomedical application as MRI contrast agents. International Journal of Nanomedicine 2007, 2, (4), 609-622. 

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