¹⁸ F-Florzolotau Positron Emission Tomography Imaging of Tau Pathology in the Living Brains of Patients with Corticobasal Syndrome

Background: Recent development in tau-sensitive tracers has sparkled significant interest in tracking tauopathies using positron emission tomography (PET) biomarkers. However, the ability of ¹⁸ F-florzolotau PET imaging to topographically characterize tau pathology in corticobasal syndrome (CBS) remains unclear. Further, the question as to whether disease-level differences exist with other neurodegenerative tauopathies is still unanswered.

Objective: To analyze the topographical patterns of tau pathology in the living brains of patients with CBS using ¹⁸ F-florzolotau PET imaging and to examine whether differences with other tauopathies exist.

Methods: ¹⁸ F-florzolotau PET imaging was performed in 20 consecutive patients with CBS, 20 cognitively healthy controls (HCs), 20 patients with Alzheimer's disease (AD), and 16 patients with progressive supranuclear palsy-Richardson's syndrome (PSP-RS). Cerebrospinal fluid (CSF) levels of β-amyloid biomarkers were quantified in all patients with CBS. ¹⁸ F-florzolotau uptake was quantitatively assessed using standardized uptake value ratios.

Results: Of the 20 patients with CBS, 19 (95%) were negative for CSF biomarkers of amyloid pathology; of them, three had negative ¹⁸ F-florzolotau PET findings. Compared with HCs, patients with CBS showed increased ¹⁸ F-florzolotau signals in both cortical and subcortical regions. In addition, patients with CBS were characterized by higher tracer retentions in subcortical regions compared with those with AD and showed a trend toward higher signals in cortical areas compared with PSP-RS. An asymmetric pattern of ¹⁸ F-florzolotau uptake was associated with an asymmetry of motor severity in patients with CBS.

Conclusions: In vivo ¹⁸ F-florzolotau PET imaging holds promise for distinguishing CBS in the spectrum of neurodegenerative tauopathies. © 2023 International Parkinson and Movement Disorder Society.