Eu II -containing cryptates as contrast agents for ultra-high field strength magnetic resonance imaging

The relaxivity (contrast-enhancing ability) of Eu(II)-containing cryptates was found to be better than a clinically approved Gd(III)-based agent at 7 T. These cryptates are among a few examples of paramagnetic substances that show an increase in longitudinal relaxivity, r(1), at ultra-high field strength relative to lower field strengths.