Centiloids in Amyloid PET: A Practical Guide to Quantitation Interpretation.

The approval of disease-modifying antiamyloid therapies has expanded the clinical role of amyloid PET beyond diagnostic confirmation to include baseline characterization and longitudinal monitoring of treatment response. Although visual interpretation remains the clinical standard for amyloid PET, it may be limited in borderline cases and when assessing subtle changes in amyloid burden over time. Quantitative amyloid PET provides objective measures that complement visual assessment, with z scores, SUV ratios, and Centiloid scaling offering increasing clinical utility. The Centiloid scale standardizes amyloid PET quantification across tracers, scanners, and institutions by anchoring measurements to biologically defined reference points, enabling consistent interpretation and comparison. This article describes the principles of amyloid PET quantification, explains the origin and interpretation of Centiloids, and discusses their role in therapy monitoring and clinical decision-making. Understanding quantitative amyloid PET and its limitations is essential for nuclear medicine professionals in the evolving landscape of Alzheimer disease imaging.