Keita Saito1, Shingo Matsumoto1, Nallathamby Devasahayam1, Sankaran Subramanian1, Jeeva P. Munasinghe2, Jan Henrik Ardenkjaer-Larsen3, Herman Douglas Morris2, Martin J. Lizak2, James B. Mitchell1, Murali C. Krishna1
1National Cancer Institute,
MRI using hyperpolarized [1-13C]pyruvate is a promising tool for cancer diagnosis, but influences of exogenously injected pyruvate on tumor physiology were not well understood. Here, effects of pyruvate injection on tumor oxygen status were investigated using pulsed electron paramagnetic resonance imaging. Tumor pO2 was remarkably decreased 30 min after [1-13C]pyruvate injection. The pO2 decrease was transient, and the pO2 recovered to the pre-injection level 5 h after the pyruvate injection. This transient decrease in the pO2 influenced effects of X-irradiation: tumor growth suppression by X-irradiation was weakened when [1-13C]pyruvate was injected to mice 30 min before X-irradiation.