Hyperpolarized Carbon-13 MRI and MRS Studies

Imaging of hyperpolarized nuclei provides significant new insights into previously inaccessible aspects of disease biology. Many of the biomolecules crucial for understanding and monitoring metabolism are present in low concentration and are often beyond the detection threshold of traditional magnetic resonance spectroscopy and imaging. A solution is to improve sensitivity by a factor of 10 000 or more by temporarily redistributing the populations of nuclear spins in a magnetic field, a process termed hyperpolarization. Nuclei such as C-13 in metabolically active biomolecules can be hyperpolarized, providing unprecedented gains in sensitivity for imaging biologic compounds. Although the first US National Cancer Institute-sponsored white paper describing the potential of this new molecular imaging technique was published only 3 years ago, over 60 biomolecules have been polarized and tested in preclinical studies. Moreover, a phase 1 clinical trial of hyperpolarized [1-C-13] pyruvate in prostate cancer patients has demonstrated that this powerful technology can be translated to the clinic. This review is focused on the dissolution dynamic nuclear polarization (DNP)-based polarization technique and summarizes the acquisition techniques used for hyperpolarized C-13 imaging, in vivo applications of some of the most promising hyperpolarized C-13 labeled biomolecules, and its clinical translation.