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Abstract #3146

Towards the Development of a Single PARACEST MRI Contrast Agent for Tumor PH Measurements

Vipul Ravindra Sheth1,2, Guanshu Liu3, Yuguo Li1, Mark D. Pagel1

1Biomedical Engineering, University of Arizona, Tucson, AZ, USA; 2Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA; 3Radiology, Johns Hopkins University, Baltimore, MD, USA

We have developed a single MRI contrast, Yb-DO3AoAA, which generate two PARAmagnetic Chemical Exchange Saturation Transfer (PARACEST) effects from an amide and amine on the agent. Because the exchange rate of protons between these two group and water have different dependencies on pH, we have shown that the ratio of these PARACEST effects is correlated with pH independent of concentration of the agent. By applying an acid-base catalyzed exchange model to the analysis of the exchange rates of these groups we have established the link between the PARACEST effects of the agent and the pH measurement.