Synopsis

Hyperpolarization of ¹³C can transiently increase its signal around 100,000 fold. This enables tracer studies in vivo of ¹³C-labelled metabolites with high time resolution. The polarization decays with a T₁ of around 30 s, necessitating innovations in hardware, sequences, and study design to capture the signal within its short longevity. The first tracer molecule taken into humans has been [1-¹³C]pyruvate. Metabolism to lactate, alanine, and bicarbonate has been shown in human brain, heart, muscle, and abdominal organs. Much interest has focused on studies in cancer, where elevations in lactate labelling related to the Warburg effect can be observed.