Comparison and cutoff values of two amyloid PET scaling methods: centiloid scale and amyloid-B load

Ann Nucl Med. 2025 Apr 26. doi: 10.1007/s12149-025-02051-6. Online ahead of print.

ABSTRACT

OBJECTIVE: To enhance amyloid-β (Aβ) positron emission tomography (PET) diagnostic accuracy and adjust for tracer differences, the amyloid-β load (Aβ_L) and centiloid (CL) scale were developed. However, the correlation and superiority of these indicators remain unclear. This study aimed to elucidate the correlation and determine cutoff values.

METHODS: Data from 281 consecutive participants (144 males; mean age, 69.6 years) in the Parkinson’s and Alzheimer’s Disease Dimensional Neuroimaging Initiative study were analyzed. Initial data, including Aβ PET, structural MRI, and Global Clinical Dementia Rating (G-CDR) scores, were reviewed. CL was calculated using the cerebral cortical and striatum Volume of Interest templates (VOI) and whole cerebellum VOI. Aβ_L was calculated using voxel-wise regression with two canonical images representing non-displaceable and specific binding. Visual estimation was performed by five radiologists, with two independently classify as visual-only Aβ-negative or Aβ-positive. The discrepancies were resolved through majority consensus involving a third observer. Additional visual estimation was performed for cases with CL value under 10 but visual-only Aβ-positive, and those over 30 but Aβ-negative, by two nuclear medicine radiologists. The discrepancies were resolved through discussion and classify as final Aβ diagnosis negative or positive.

RESULTS: CL and Aβ_L correlated linearly (CL = Aβ_L × 2.10-9.40, R² = 0.923). In predicting final Aβ diagnosis negative versus positive, both CL (AUC = 0.996) and Aβ_L (AUC = 0.997) were significant, with no significant differences (P = 0.882). The Youden Index was 23.3 for CL and 15.6 for Aβ_L. In predicting cognitively normal participants (G-CDR = 0) from others, both CL (AUC = 0.687) and Aβ_L (AUC = 0.667) were significant, with no significant differences (P = 0.379). The Youden Index was 11.9 for CL and 11.6 for Aβ_L. Using a non-biased Gaussian mixture model, the normal group’s mean and SD were -2.5 (SD = 6.5) for CL and 3.7 (SD = 3.0) for Aβ_L, resulting in 95% limits (mean + 2SD) of 10.4 for CL and 9.7 for Aβ_L.

CONCLUSIONS: This study demonstrated a high correlation and non-inferiority between CL and Aβ_L.

PMID:40285971 | DOI:10.1007/s12149-025-02051-6