Europium contrast agents

The only data that have been provided on Gd levels in plasma and urine of healthy subjects were those of Allain et al. [16] reporting normal concentrations of the element in these biological fluids to be <0.3 p.g/liter. Data on the tissue distribution of Gd are scarce. As for some other medium lanthanides, i.e., the subgroup of lanthanides that comprises the elements from europium (Eu) to holmium (Ho), the element is supposed to be equally deposited in the liver and the skeleton [2]. Administration of Gd-DOTA and Gd-DTPA contrast agents in rats resulted in a 0. l-1.0% retention in liver and spleen [17]. 

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