[11 C]PBB3 binding in Aβ(-) or Aβ(+) corticobasal syndrome.

Corticobasal syndrome (CBS) is associated with 4-repeat tauopathy and/or Alzheimer's disease pathologies. To examine tau and amyloid-β (Aβ) deposits in CBS patients using positron emission tomography (PET). Eight CBS patients and three healthy individuals lacking amyloid pathology underwent PET with [¹¹ C]PBB3 for tau imaging, and [¹¹ C]AZD2184 for Aβ. Subcortical and cortical binding of [¹¹ C]PBB3 was compared between Aβ(-) and Aβ(+) CBS patients and reference group. Postmortem analysis was done in one CBS patient. Three CBS patients were considered Aβ(+). Total binding was higher in all patients compared to the reference group. Similar regional binding profiles of [¹¹ C]PBB3 in Aβ(+) and Aβ(-) CBS patients were found. Elevated [¹¹ C]PBB3 binding in pallidum was observed in all CBS patients. Cortical [¹¹ C]PBB3 binding was higher in Aβ(+) compared to Aβ(-) patients. Postmortem analysis of a CBS patient revealed corticobasal degeneration neuropathology and [¹¹ C]PBB3 autofluorescence in some tau-positive structures. [¹¹ C]PBB3 is elevated in CBS patients with binding in relevant areas capturing some, but not all, 4-repeat tauopathy in CBS.