Abstract:

Superparamagnetic iron oxides (SPIO) are known for their fast T₂ (T*₂) relaxation properties which result in a strong decrease in signal intensity (negative enhancement) of such reticuloendothelial system as the liver, the spleen, and et al where they accumulate. For its low solubility in water, SPIO usually  are colloidally coated and stabilized with a matrix such as dextran or liposomes . In this work, a series of micelle coated and stabilized SPIO colloids were pre pared and the T₂ values of these SPIO micells were measured, aiming to in vestig ate the effect of properties of different micelles on SPIO solution. The experim ental data showed that both different kind of charge which the micelle has and t he molecular weight of surfactant have distinct effect on the T₂ relaxation of SPIO colloid. The SPIO colloid coated by PEG-400 was selected for the acute toxi city and MR imaging contrast test. The results indicated that there was no obviou s toxicity for this polymeric micelle coated SPIO colloid, and mini dose (20 μm o l/kg) of SPIO exhibits the obvious negative enhanced MRI signal intensity in the  rat liver tissue.

Key words: superparamagnetic iron oxides (SPIO), micelle, liver targeting contrast, T₂ weighted magnetic resonance imaging, negative enhancement