MAPT and Parkinson disease: Of these, quantitative susceptibility mapping (QSM) is particularly promising as it relates to accumulation of brain tissue iron, which is strongly linked with neurodegeneration (Ward et al., 2014; Ndayisaba et al., 2019), co-localizes with amyloid and tau (Ayton et al., 2017), and correlates with cognitive change in Parkinson’s disease (Thomas et al., 2020).