State-of-the-art accounts of hyperpolarized 15 N-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 15 N-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 13 C nuclei. This review will present recent developments of these hyperpolarized 15 N-labeled molecular imaging probes, ranging from endogenous and drug molecules, and chemical sensors, to various 15 N-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 15 N-based biomedical imaging agents and their applications.