CytoCEST: Cells as CEST Agents

Giuseppe Ferrauto¹, Daniela Delli Castelli¹, Enza Di Gregorio¹, Enzo Terreno¹, Holger Gruell², Silvio Aime¹

CEST agents are able to generate a frequency-encoded contrast allowing the simultaneous detection of multiple agents in the same voxels. Unfortunately they suffer for a low sensitivity. Since sensitivity depends on the number of equivalent mobile protons irradiated, systems bearing huge numbers of exchanging protons have been developed. In this work we report a labeling procedure allowing to exploit the huge number of intracellular water protons to generate CEST contrast. The separation between the NMR signal of bulk and intracellular water protons is provided by entrapping inside the cell a paramagnetic shift reagent. This new system has been named cytoCEST.