A Stable Nitroxide Radical as a Contrast Agent for Magnetic Resonance Imaging

摘要

Currently, compounds containing a paramagnetic metal ion (Gd~(3+), Mn~(3+), Fe~(3+)) are used as contrast agents in magnetic resonance imaging (MRI). Free transition metal ions are highly toxic and, therefore, should be introduced into the living body in the form of thermo-dynamically stable complexes with polydentate Uganda; the latter are mainly specially synthesized complexones. Bulky complexone molecules (i) inevitably increase the distance between the paramagnetic center and the molecular environment, which decreases the efficiency of coupling of nuclear spins to unpaired electrons of the metal ion, and (ii) are not among natural metabolites, which makes them foreign substances in organisms.