Hyperpolarized (HP) 13C labeled compounds can be used as MR contrast agents to investigate metabolic pathways in vivo in almost real time. To date, a high proportion of reported studies have utilized HP 1-13C pyruvate to investigate intracellular metabolism in tumors and other tissues. The long T1 relaxation time of the carboxylate carbon enables the 13C signal of the pyruvate to be followed for nearly 2 minutes following injection. During this time, pyruvate is rapidly metabolized to generate observable metabolites such as alanine and lactate. HP 13C labeled compounds have, for example, also been used to non-invasively probe physiological parameters such as pH, which emphasizes the expanding potential of the technique. The commercial availability of dynamic nuclear polarization (DNP) systems to generate hyperpolarized material for injection has made the technique available to researchers worldwide. As a consequence, DNP 13C MR has become a rapidly expanding area of research. The technique, with its specific strengths and weaknesses, has incredible potential coupled with inherent limitations, and this review aims to both present background to the technique and describe some of the necessary hardware and software essential to perform hyperpolarized 13C studies. An overview of the current and future role of HP 13C based molecular imaging is presented.
Keywords: Hyperpolarization, 13carbon, dynamic nuclear polarization, pyruvate, T1 relaxation, MRI, MRS, molecular imaging
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