Subcortical ¹⁸F-AV-1451 binding patterns in progressive supranuclear palsy

Background: Accumulation of cortical and subcortical tau pathology is the primary pathological substrate for progressive supranuclear palsy (PSP). ¹⁸F-AV-1451, a radiotracer that binds to the pathological tau protein, may be helpful for in vivo visualization and quantitation of tau pathology in PSP. Objectives: The objectives of this study were to investigate cortical and subcortical ¹⁸F-AV-1451 binding patterns in patients with PSP. Methods: We recruited 14 PSP patients and compared their cortical and subcortical binding patterns in ¹⁸F-AV-1451 positron emission tomography (PET) studies with those of 15 Parkinson's disease (PD) patients and 15 healthy controls. Results: In both the PD and PSP groups, subcortical ¹⁸F-AV-1451 binding did not correlate with the severity of motor dysfunctions, and cortical binding did not differ between the controls and each patient group. However, the PSP patients showed greater ¹⁸F-AV-1451 binding in the putamen, globus pallidus, subthalamic nucleus, and dentate nucleus when compared with the controls, whereas the PD patients showed lower ¹⁸F-AV-1451 binding in the substantia nigra than controls. Conclusions: The PSP and PD patients showed distinct subcortical ¹⁸F-AV-1451 binding patterns reflecting subcortical tau pathology in PSP and reduced nigral neuromelanin in PD. However, there was no correlation with the severity of motor dysfunction, no cortical regions with increased binding in PSP patients, and variable degrees of subcortical binding even in the controls. Therefore, the ¹⁸F-AV-1451 PET may be less than ideal for assessing tau pathology in PSP. Further studies will be required to validate the clinical correlation and to understand the clinical utility of ¹⁸F-AV-1451 PET for PSP patients.