Tau positron emission tomography in the Parkinson and Richardson subtypes of progressive supranuclear palsy.

Progressive supranuclear palsy (PSP) is an atypical form of parkinsonism affected by deficiencies regarding efficient methods of examination, thereby hindering the establishment of an early and certain diagnosis prior to post-mortem examination. Most studies are based on magnetic resonance imaging analyses; however, there is growing interest in the evaluation of radiotracers in positron emission tomography (PET). In this narrative review, we attempt to elaborate on the significance of tau radiotracers and other PET biomarkers in the context of examination of two major subtypes of PSP: Richardson's syndrome (PSP-RS) and parkinsonism predominant (PSP-P). Although the subtypes show clinical boundaries and overlaps, they may be additionally evaluated using in vivo tau imaging. The feasibility of these methods may vary depending on cell-specific accumulation. The assessment of discrepancies in cellular tau deposition, as well as the combined analysis of these features with the pathogenesis of PSP-RS and PSP-P, may provide further insights enabling the redefinition of the diagnosis and monitoring of these conditions and the formulation of efficient therapeutic strategies.