Amyloid PET Quantitation and Centiloid Thresholds in the Diagnosis of Alzheimer Disease: An Individual Participant Data Meta-Analysis.

A single Centiloid cutoff of 18 best distinguishes amyloid positivity in PET scans across diverse studies, with a high predictive value for visual reads.

• Why it matters: Standardized thresholds are essential for consistent diagnosis and treatment decisions in Alzheimer disease, but variability in methods complicates interpretation.
• What they did: The study pooled individual data from 53 studies involving 49,227 participants, applying Gaussian mixture models and visual read correspondence to determine robust positivity cutoffs.
• The result: Positivity cutoffs converged around 18 Centiloids for data-driven methods and 27 Centiloids for visual read agreement, with a cautious interpretation range between 11 and 26 Centiloids.