Non-porphyrin multipurpose contrast agents

Compounds (see Fig. 2) comprising a nitrogen-containing heterocyclic ring system covalently bonded to a carbocyclic or heterocyclic ring system by a direct link or optionally substituted linking agent. The ring systems and linking agent may be substituted by metal chelating structures which allow labelling of the compound by complexation with metal ions such as gadolinium ions. The compounds may be used in pharmaceutical compositions which are useful for therapeutic and/or diagnostic applications including nuclear scintigraphy and magnetic resonance imaging and may be used as multipurpose contrast agents for the identification and visualisation of necrosis.