Figure 3: Real time detection of hyperpolarized 13C succinate and its metabolites in lymphoma A20 in a living mouse. The mouse received 10 μmoles hyperpolarized SUC by tail vein injection. A. Metabolic products from hyperpolarized 13C SUC (the largest peak) were detected in the tumor within 10 seconds of the injection of hyperpolarized substrate (pH 3 – 4.5) and persisted for 45 seconds. Using the 3 M 13C acetate phantom (non-hyperpolarized) as chemical shift reference, metabolites are defined as C1 and C4 malate. B. The corresponding Krebs cycle of oxidative tumor metabolism in lymphoma A20 is illustrated. Krebs cycle metabolite pools which reproducibly become enriched from exogenous 13C succinate within the T1 of hyperpolarization are indicated in boxes and differ markedly from those in RENCA.