Partner und Internationale Organisationen
(Englisch)
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A, B, CH, CZ, D, DK, E, F, FIN, GR, H, I, IRL, N, NL, P, ROM, S, Sl
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Abstract
(Englisch)
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The development of high relaxivity compounds is still an important issue in contrast agent research for Magnetic Resonance Imaging. In order to be able to ameliorate the efficiency of GdIII complexes as contrast agents, one has to understand which parameters and through which mechanisms influence proton relaxivity of these agents. Slow water exchange is a factor that often limits proton relaxivity of GdIII complexes, especially for the new generation, high molecular weight compounds. Different factors, such as a hydration equilibrium or the presence of isomers that modify the water exchange process have been assessed for tetraazamacrocyclic GdIII chelates. Electron spin relaxation constitutes the least understood part of the theory describing the relaxation of Gd(III) based paramagnetic species. Based on the experimental results of variable temperature, multiple field EPR measurements in a large magnetic field range, which became available only recently, we have substantially improved the electron spin relaxation theory. Complexes of EuII/EuIII can be potential redox switches used as contrast agents in Magnetic Resonance Imaging. The EuII is isoelectronic with GdIII, therefore relatively high proton relaxivities can be expected for EuII complexes, whereas the EuIII analogues have very low relaxivity. In this perspective, we have studied the EuII aqua ion as well as EuII(DTPA) complex.
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