PET-based classification of corticobasal syndrome

Area of Science:

• Neuroscience
• Neuropathology
• Radiology

Background:

• Corticobasal degeneration (CBD) is the primary cause of corticobasal syndrome (CBS), but diagnosing CBD pathology in living patients is difficult.
• Positron emission tomography (PET) offers a potential in vivo method for detecting CBD-related tau depositions.

Purpose of the Study:

• To evaluate the capability of PET imaging to detect CBD-type tau deposits.
• To assess the utility of PET in the neuropathological classification of CBS.

Main Methods:

• Sixteen CBS patients and 12 healthy controls (HCs) underwent PET scans (¹¹C-PiB, ¹¹C-PBB3, ¹⁸F-FDG) and MRI.
• Amyloid and tau positivity were determined using ¹¹C-PiB and ¹¹C-PBB3 retention, respectively, compared to HCs.

Main Results:

• Of 16 CBS cases, 13% had AD pathology, 69% had amyloid-negative tau positivity, and 19% had both amyloid and tau negativity.
• Amyloid-negative, tau-positive CBS cases showed increased ¹¹C-PBB3 uptake in frontoparietal areas, basal ganglia, and midbrain, with reduced metabolism in the precentral gyrus and thalamus.
• Increased tau probe retention in frontal regions correlated with metabolic deficits, atrophy, and Clinical Dementia Rating scores.

Conclusions:

• PET-based classification of CBS aligns with neuropathological findings for Alzheimer's disease and other tauopathies.
• ¹¹C-PBB3-PET shows promise for biologically classifying CBS and elucidating the relationship between CBD-type tau and neurodegeneration.