Rahul Gaurav, PhD, Paris Brain Institute, Paris, France, explains how advances in neuroradiology allow us to clinically define the progression from isolated REM sleep behavior disorder (iRBD) to Parkinson’s disease (PD). Neuromelanin-sensitive MRI (NM-MRI) allows visualization of the substantia nigra pars compacta (SNc) and the locus coeruleus. Segmentation of these regions to examine iron content has revealed a progressive increase in iron deposition in the SNc from healthy volunteers to prodromal iRBD to PD patients. Iron deposition likely contributes to a heightened pro-oxidant environment in dopaminergic neurons, making it an important biomarker for monitoring disease progression and in therapy assessment. This interview was recorded at the World Sleep Congress 2022 in Rome, Italy.