A comparison of advanced semi-quantitative amyloid PET analysis methods

Area of Science:

• Neuroimaging
• Nuclear Medicine
• Radiochemistry

Background:

• Semi-quantitative assessment of brain amyloid Positron Emission Tomography (PET) lacks a standardized approach.
• Existing methods include those using late acquisition alone (e.g., ELBA), early acquisition (e.g., TDr), or integrating structural imaging (e.g., WMR, SI).

Purpose of the Study:

• To compare the efficacy and feasibility of various semi-quantitative brain amyloid PET assessment methods in a clinical setting.
• To establish a reference measure for amyloid burden using the most comprehensive approach (SI).

Main Methods:

• Compared Standardized Uptake Value Ratio (SUVr), Early Late Brain Amyloid (ELBA), Time-dependent perfusion (TDr), White Matter to Grey Matter Ratio (WMR), and Standardized Imaging (SI) in 85 patients using dual time-point PET/MRI.
• Computed correlations with SI, compared methods against visual assessment, and linearly combined independent measures.
• Investigated associations between quantifiers and age in amyloid-negative patients.

Main Results:

• All quantifiers showed excellent agreement with visual assessment and strong correlation with SI (average AUC=0.99, ρ=0.91), with exceptions in subcortical regions for ELBA and WMR.
• Linear combinations of methods outperformed individual approaches.
• Significant associations were found between TDr, WMR, SI, and age in amyloid-negative patients (p<0.05).

Conclusions:

• The TDr method offers a balance of performance and implementation simplicity, closely approximating the reference SI measure.
• Combining independent quantification approaches yields superior results compared to individual methods, suggesting a focus on multi-classifier systems for amyloid PET.
• Techniques incorporating blood perfusion effectively illustrate age-related amyloid load variations in amyloid-negative individuals.