A universal neocortical mask for Centiloid quantification.

Area of Science:

• Neuroimaging
• Biomarker Quantification
• Alzheimer's Disease Research

Background:

• The Centiloid (CL) project harmonizes amyloid beta (Aβ) positron emission tomography (PET) quantification using a standardized scale.
• The standard CL neocortical mask, based on ¹¹C Pittsburgh compound B (PiB), may not fully account for regional distribution differences across various Aβ tracers.

Purpose of the Study:

• To develop and evaluate a universal neocortical mask for Aβ PET imaging.
• To assess the impact of this universal mask on inter-tracer agreement, tracer variability, and diagnostic group separation.

Main Methods:

• A universal mask was created using a dataset of five Aβ tracers (¹⁸F-florbetapir, ¹⁸F-florbetaben, ¹⁸F-flutemetamol, ¹⁸F-NAV, ¹¹C-PiB) from the ADOPIC study.
• The mask was evaluated on its ability to improve inter-tracer agreement and group separation (Healthy Controls/Alzheimer's Disease and Healthy Controls/Mild Cognitive Impairment) using GAAIN and ADOPIC datasets.

Main Results:

• The universal mask demonstrated a slight reduction in variance among young controls and a minor increase in inter-tracer agreement in the GAAIN dataset.
• In the ADOPIC dataset, the universal mask showed improved separation between healthy controls and individuals with Alzheimer's disease or mild cognitive impairment at baseline.

Conclusions:

• The universal Centiloid mask offers marginal benefits in inter-tracer agreement and group separation.
• These improvements are not substantial enough to warrant replacing the existing standard CL mask, which is effective for quantifying all Aβ tracers.