Phillip Zhe Sun1, Dario L. Longo2, Silvio Aime2
1Radiology, Athinoula. A. Martinos Center for Biomedical Imaging, MGH & Harvard Medical School, Charlestown, MA, United States; 2Chemistry, IFM & Molecular Imaging Centre, University of Torino, Torino, Italy
Whereas chemical exchange saturation transfer (CEST) MRI is capable of imaging microenvironment pH, the CEST contrast also varies with the labile proton concentration. To solve this confounding factor, ratiometric CEST MRI has been proposed that interrogates CEST effects of multiple distinguishable labile groups so their concentration effect can be normalized. Specifically, iopamidol, a widely used CT agent, has been recently explored for imaging renal pH. Here, we evaluated iopamidol CEST MRI with multi-pool chemical exchange, and showed that both amide and 2-hydrooxypropanamido proton groups are base-catalyzed exchange, suitable for imaging pH from 6 to 7.5.