Preliminary work by the Clinical Research Unit KFO 213 suggests that gadolinium-containing contrast media can deliver the gadolinium ion to highly sulphated glycosaminoglycans, which occur more frequently in inflamed tissue. Although this transchelation process occurs only to a very small extent, it offers the potential to serve as a specific marker for imaging pathological changes in the extracellular matrix. Therefore, it is necessary to investigate the possible influence of this process on contrast enhancement in glycosaminoglycan-containing tissue. In collaboration, we use electron spin resonance spectroscopy to identify and characterise binding motifs for gadolinium in glycosaminoglycans.