Highly Sensitive MRI Chemical Exchange Saturation Transfer Agents Using Liposomes

Chemical exchange saturation transfer (CEST) agents represent an emerging class of magnetic resonance imaging (MRI) contrast media that has huge potential. They act as negative agents by reducing the signal intensity of the water protons through a saturation transfer mediated by chemical exchange. The results reported here show that LIPOCEST agents represent an innovative class of MR imaging probes of outstanding sensitivity (per liposome). Moreover, as the chemical shift of water entrapped within the liposomes depends upon the nature and concentration of the shift reagent as well as on the permeability of the liposome membrane, one may envisage facile access to a number of LIPOCESTagents with different absorption frequencies. This approach will allow a dramatic extension of the experiments that can be carried out by having the possibility of irradiating the various LIPOCEST agents present in the same sample specifically.