Figure 3.

Hyperpolarized [1-¹³C]pyruvate MRI detects the metabolic consequences of ischemic stroke and reperfusion in pigs. Hyperpolarized [1-¹³C]pyruvate was injected and the pyruvate and downstream metabolites were visualized with MRI (a, au = arbitrary unit). The anaerobic pyruvate-to-lactate exchange is sensitive to hypoxia. It was estimated through quantification of the rate constant (k_PL, (b) and (c), red ring marks infarct) and using model-free ratio approaches (d) that showed increased lactate production during ischemia, which decreased to sub-normal levels after reperfusion. Image examples are shown as one representative slice summed through time. Data are shown as individual observations (n = 4–7) with mean ± SD. Tested with linear mixed-effect models. ROI is region of interest, t is time, the colon (:) marks an interaction.