In vivo dynamic nuclear polarization MRI for the evaluation of redox-related diseases and theranostics

Significance In vivo molecular and metabolic imaging is an emerging field in biomedical research that aims to perform noninvasive detection of tissue metabolism in disease states and responses to therapeutic agents. The imbalance in tissue oxidation/reduction (Redox) states is related to the onset and progression of several diseases. Tissue redox metabolism provides biomarkers for early diagnosis and drug treatments. Thus, noninvasive imaging of redox metabolism could be a useful, novel diagnostic tool for diagnosis of redox-related disease and drug discovery. Recent Advances: In vivo dynamic nuclear polarization magnetic resonance imaging (DNP-MRI) is a technique that enables the imaging of free radicals in living animals. DNP enhances the MRI signal by irradiating the target solution or tissue at the electron paramagnetic resonance frequency of the free radical molecule before executing the MRI pulse sequence. In vivo DNP-MRI with redox-sensitive nitroxyl radicals as the DNP redox contrast agent enables the imaging of the redox metabolism on various diseases. Moreover, nitroxyl radicals show antioxidant effects that suppress oxidative stress. Critical issues To date, considerable progress has been documented preclinically in the development of animal imaging systems. Here, we review redox imaging of in vivo DNP-MRI with a focus on the recent progress of the in vivo DNP-MRI system and its application in patients with redox-related diseases. Future Directions: This technique could have broad applications in the study of other redox-related diseases, such as cancer, inflammation, and neurological disorders, and facilitate the evaluation of treatment response as a theranostic tool.