TSPO and Parkinson disease: The extent of neuroinflammation in PD patients has been studied with TSPO PET tracers (R)‐[11C]PK11195 (Gerhard et al., 2006; Ouchi et al., 2005), [11C]PBR28 (Varnäs et al., 2019) and [18F]FEPPA (Ghadery et al., 2017).