State-of-the-art accounts of hyperpolarized 15N-labeled molecular imaging probes for magnetic resonance spectroscopy and imaging

Hyperpolarized isotope-labeled agents have significantly advanced nuclear magnetic resonance spectroscopy and imaging (MRS/MRI) of physicochemical activities at molecular levels. An emerging advance in this area is exciting developments of N-15-labeled hyperpolarized MR agents to enable acquisition of highly valuable information that was previously inaccessible and expand the applications of MRS/MRI beyond commonly studied C-13 nuclei. This review will present recent developments of these hyperpolarized N-15-labeled molecular imaging probes, ranging from endogenous and drug molecules, and chemical sensors, to various N-15-tagged biomolecules. Through these examples, this review will provide insights into the target selection and probe design rationale and inherent challenges of HP imaging in hopes of facilitating future developments of N-15-based biomedical imaging agents and their applications.