Room: AAPM ePoster Library
Purpose: The activity of anaerobic glycolysis reaction may be detected in-vitro or in-vivo by ¹³C MRS of hyperpolarized (HP) substrates. The dynamic signals from HP substrates and products have been fitted to a number of mathematical models to determine chemical reaction rates. However, in our study, the traditional model with chemical reaction rate constants has shown a large difference between the model and our results. Here, we have introduced a correction term, the chemical reaction rate in anaerobic glycolysis as a function of time, into the traditional model to minimize the discrepancy.
Methods: Our kinetic model for the detection of ¹³C-enriched lactate after the administration of labeled pyruvate is to consider bidirectional three pools: intracellular pyruvate, intracellular lactate, and extracellular pyruvate. In addition, with consideration of the effects of T1, radiofrequency (RF) excitation, and the dynamic chemical reaction rate, this three-pool model becomes rather complex. For our in vitro experiment, THP1 6x107 cells were in 9 ml medium. The HP ¹³C pyruvate, 1 ml, was poured into this medium. HP ¹³C signal in this medium was acquired by generic ¹³C MRS in 3T. The mixing and delivery of substrate and cells were at different time points and recorded. These time records were reference points in our model.
Results: For the pyruvate comparison between two kinetic models and experimental data, the maximum difference was about 35%! However, for the dynamic lactate comparison, the difference between the real data and the traditional model (51%) was larger than that between the real data and our model (37%) when SNR=4. Although the correction term did not cause any change in substrate, it has provided ¹³C lactate better fitting in our data.
Conclusion: The correction term in our three-pool model was necessary to explain and fit the experiential data. The further validation is still needed.