Imaging Regional Metabolic Changes in the Ischemic Rat Heart In Vivo Using Hyperpolarized [1-(13)C]Pyruvate

We evaluated the use of hyperpolarized (13)C magnetic resonance imaging (MRI) in an open-chest rat model of myocardial infarction to image regional changes in myocardial metabolism. In total, 10 rats were examined before and after 30 minutes of occlusion of the left anterior descending coronary artery using hyperpolarized [1-(13)C]pyruvate. Cardiac metabolic images of [1-(13)C]pyruvate and its metabolites [1-(13)C]lactate, [1-(13)C]alanine, and [(13)C]bicarbonate were obtained before and after ischemia. Significant reduction in the [1-(13)C]alanine and [1-(13)C]lactate signals were observed in the ischemic region post ischemia. The severity of the ischemic insult was verified by increased blood levels of troponin I and by using late contrast-enhanced MRI that showed enhanced signal in the ischemic region. This study shows that hyperpolarized MRI can be used to image regional metabolic changes in the in vivo rat heart in an open-chest model of ischemia reperfusion. Hyperpolarized MRI enables new possibilities for evaluating changes in cardiac metabolism noninvasively and in real time, which potentially could be used for research to evaluate new treatments and metabolic interventions for myocardial ischemia and to apply knowledge to future application of the technique in humans.