Amyloid PET Quantitation and Centiloid Thresholds in the Diagnosis of Alzheimer Disease

Which Centiloid value should serve as the cutoff for classifying an amyloid positron emission tomographic (PET) scan as positive for amyloid?In this individual participant data meta-analysis that included 53 studies and 49 227 participants, positivity cutoffs were derived using both a data-driven method and correspondence to a visual reads method, resulting in the meta-estimated cutoffs of 18 and 27 Centiloids, respectively. Using a double-cutoff approach, scans can be interpreted with high confidence as negative for amyloid if values are lower than 11 Centiloids and as positive for amyloid if they are higher than 26 Centiloids.Binary amyloid PET positivity cutoffs cluster around 18 to 27 Centiloids. A double-cutoff approach suggests that scans with Centiloid values in the 11 to 26 range should be interpreted with caution depending on the context of use.

Corresponding Author: Ganna Blazhenets, PhD, Edward and Pearl Fein Memory and Aging Center, Department of Neurology, Weill Institute for Neurosciences, University of California, San Francisco, 654 Minnesota St, Ste 146, Room 154, San Francisco, CA 94107 (ganna.blazhenets@ucsf.edu).

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