Hyperpolarized C-13 Metabolic Activity Decomposition with Stimulated-echoes

Peder Eric Zufall Larson¹, Adam B. Kerr², John M. Pauly², Daniel B. Vigneron¹

In hyperpolarized 13C metabolic imaging, the metabolic profile is assumed from indirect observations of converted metabolites. We have developed a method using the stimulated echo for directly observing localized conversion/label exchange from hyperpolarized [1-13C]pyruvate to [1-13C]lactate and [1-13C]alanine in vivo. It is based on a phase-sensitive stimulated-echo tagging, which also selects only stationary metabolites. Metabolites generated from stationary pyruvate during the mixing interval have a 90-degree phase shift from those present prior to the tagging. Generated metabolites are separated using a phase-sensitive reconstruction. In vivo experiments have demonstrated direct observation of both alanine and lactate generation, allowing for a more accurate metabolic characterization.