Chemistry of tumour targeted T1 based MRI contrast agents

For effective tumour imaging by magnetic resonance imaging (MRI) there is a clear need to develop organ, tissue and cell specific contrast agents that can selectively bind to tumour biomarkers. The versatility of a range of bioconjugation techniques and facile coupling chemistries has facilitated the synthesis of MRI contrast agents bearing tumour targeting moieties that comprise small molecule affinity ligands, peptides, antibodies and even proteins. The aim of this review is to describe the development and implementation of tumour targeted T(1) MRI contrast agents, with an emphasis on the chemistry used to modify pre-existing clinical MRI contrast agents for targeted tumour imaging.