Current and potential applications of clinical 13C MR spectroscopy

In this article, the current and potential clinical roles of C-13 magnetic resonance spectroscopy (MRS) and C-13 magnetic resonance spectroscopic imaging are presented, with a focus on applications to prostate cancer and hyperpolarized C-13 spectroscopic imaging. The advantages of C-13 MRS have been its chemical specificity and lack of background signal, with the major disadvantage being its inherently low sensitivity and the subsequent inability to acquire data at a high-enough spatial and temporal resolution to be routinely applicable in the clinic. The approaches to improving the sensitivity of C-13 spectroscopy have been to perform proton decoupling and to use endogenous C-13-labeled or enhanced metabolic substrates. With these nominal increases in signal-to-noise ratio, C-13 MRS using labeled metabolic substrates has shown diagnostic promise in patients and has been approved by the Food and Drug Administration. The development of technology that applies dynamic nuclear polarization to generate hyperpolarized C-13-labeled metabolic substrates, and the development of a process for delivering them into living subjects, have totally changed the clinical potential of MRS of C-13-labeled metabolic substrates. Preliminary preclinical studies in a model of prostate cancer have demonstrated the potential clinical utility of hyperpolarized C-13 MRS.