Identifying and characterizing the anatomic architecture of the substantia nigra (SN) has important clinical implications for the evaluation of structural changes associated with neurodegenerative conditions, such as Parkinson’s disease (PD)123. The SN is subdivided into two histologically distinct regions, the ventral pars reticulata (SNr) and the dorsal pars compacta (SNc). The SNc is composed of neuromelanin (NM)-containing dopaminergic neurons, which are affected early in PD123.