Ralph Hurd1, Daniel Spielman2, Sonal Josan3, Jae Mo Park4, Yi-Fen Yen1, Adolf Pfefferbaum3, 5, Dirk Mayer, 23
1GE Healthcare, Menlo Park, CA, United States; 2Radiology, Stanford University, Stanford, CA, United States; 3Neuroscience Program, SRI International, Menlo Park, CA, United States; 4Electrical Engineering, Stanford University, Stanford, CA, United States; 5Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, United States
In hyperpolarized [1-13C]pyruvate and hyperpolarized [1-13C]lactate metabolic imaging, the pool size of the exchange partner may limit the rate of isotopic mixing. This is especially true for hyperpolarized [1-13C]lactate metabolic imaging, given the small steady-state pyruvate pool. Under conditions where addition of unlabeled exchange partner to the bolus results in a linear increase in rate, absolute values for exchange rate constant (Kexchange) can be determined in both directions. In this study we show that such conditions appear to be true for a bolus of 80mM pyruvate and 40 mM lactate in rat kidney, and use the dynamic imaging data to calculate Kexchange.