Figure 2. The chemical structure of cytidine- based agents (a) and their CEST MRI contrast, as shown both by z-spectra (b & c) and MTR^asym plots (b & d).

All samples were prepared in PBS (pH 7.4) at a concentration of 20 mM and measured at 37°C using a 3.6 μT, 3 sec CW RF pulse.