Investigation of magnetic properties of various complexes prepared as contrast agents for MRI

In this study, the relaxivities of various ferri–ferro and superparamagnetic particles in human serum and deionized water were determined by using MRI system operating at 1.5 T. For this purpose, the spin–lattice (1/T1) and spin–spin (1/T2) relaxation rates in serum and deionized water were measured versus increasing concentrations of the DyPO4, 5Fe2O33Gd2O3 + dextran, 5Fe2O33Gd2O3 + CMC, 5Fe2O33Gd2O3. The longitudinal relaxivity (r1) and transverse relaxivity (r2) of proton were determined from the slopes of fits between the relaxation rates and concentrations. T2 times in serum were decreased due to increased concentrations of the ions added to samples. The r2/r1 values for ions added to serum ranged from 1 to 4, whereas the r2/r1 for the ions added to water changed between 0.57 and 1 except that for 5Fe2O33Gd2O3. PRRE (proton relaxation rate enhancement) data reveals that, the ions added to serum are not bound to the proteins. The present results suggest that chemical compounds of iron oxide studied may have a potential that can be used as an alternative superparamagnetic MRI contrast agent.