Alex Xuexin Li1,2, Craig K. Jones1, Mojmir Suchy1,3, Robert H.E. Hudson3, Ravi S. Menon1,2, Robert Bartha1,2
1Center for Functional and Metabolic Mapping, Robarts Research Institute, London, ON, Canada; 2Department of Medical Biophysics, The University of Western Ontario, London, ON, Canada; 3Department of Chemistry, The University of Western Ontario, London, ON, Canada
A technology to measure pH using the amide protons site of a thulium complex with a DOTAM-Glycine-Lysine ligand: Tm3+-DOTAM-Gly-Lys was developed. The pH can be determined uniquely from the linewidth of the asymmetry curve of the CEST spectrum in a manner independent of contrast agent concentration, intrinsic magnetization transfer effect, and temperature for a given saturation pulse. pH maps with standard deviation less than 0.1 pH units were obtained from 10 mM Tm3+-DOTAM-Gly-Lys solutions with different pH.