MRI Paramagnetic Probes for Cellular Labeling

This review discusses the main procedures that have been developed for pursuing the task of an efficient cellular labelling with paramagnetic metal complexes for MRI detection. Although most of the work deals with GdIII‐based relaxation enhancers it is shown that the emerging class of paraCEST agents can allow the visualization of more cell types in the same MR image. To improve the detection of labelled cells, it is often necessary to deal with the use of nano‐sized carriers able to deliver a large number of paramagnetic metal complexes. Finally, selected examples are reported to show how proper design of the paramagnetic complex can offer the way to acquire key information on underlying processes in the labelled cells. The main procedures which allow an efficient cellular labelling with paramagnetic metal complexes for MRI detection are discussed. Systems which use GdIII and MnII‐based relaxation enhancers as labeling probes have been considered, as well as the emerging class of paraCEST agents which allows the visualization of more cell types in the same MR image.