Abstract #4496

Using the Linewidth of the Amide Proton CEST Effect of MRI-PARACEST Agents for PH Mapping

Alex Xuexin Li^1,2, Craig K. Jones¹, Mojmir Suchy^1,3, Robert H.E. Hudson³, Ravi S. Menon^1,2, Robert Bartha^1,2

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.