TSPO and Parkinson disease: The aim of this systematic review is to provide an overview of the existing literature regarding PET radioligands targeting TSPO in patients affected by Parkinson’s Disease in order to understand which are the goals and future perspectives in terms of early diagnosis and treatment of neuroinflammation and its implication in the pathogenesis of PD by means of correlation between neuroinflammation and other pathogenic pathways as the dopaminergic pathway damage and β-amyloid deposition.