Assessing oxidative stress in tumors by measuring the rate of hyperpolarized [1-13C] dehydroascorbic acid reduction using 13C magnetic resonance spectroscopy מאת Timm, KN, Hu, D-E, Williams, M, Wright, AJ, Kettunen, MI, Kennedy, BWC, Larkin, TJ, Dzien, P, Marco-Rius, I, Bohndiek, SE, Brindle, KM