Identifying Mild Alzheimer's Disease With First 30-Min ¹¹C-PiB PET Scan

Area of Science:

• Neurology
• Radiology
• Biomedical Imaging

Background:

• ¹¹C-labeled Pittsburgh compound B (¹¹C-PiB) PET imaging aids Alzheimer's disease (AD) diagnosis by quantifying brain β-amyloid deposition.
• Current quantification methods like SUVR and DVR require lengthy scans and reference region selection.
• There is a need for faster, more efficient methods to assess amyloid burden in AD.

Purpose of the Study:

• To introduce and evaluate a novel measure, the amyloid quantification index (AQI), for diagnosing AD.
• To assess AQI's performance using a short, 30-minute PET scan without a reference region.
• To compare AQI's diagnostic accuracy against established SUVR and DVR measures.

Main Methods:

• Utilized the OASIS-3 dataset with 60 mild AD patients and 60 healthy controls (50 for training, 10 for testing per group).
• Developed AQI by combining early-phase clearance rate and mid-phase ¹¹C-PiB retention.
• Employed logistic regression for classification and ROC analysis to evaluate AQI, SUVR, and DVR performance, alongside Kruskal-Wallis tests and effect size calculations.

Main Results:

• AQI, SUVR, and DVR all significantly differentiated between healthy controls and mild AD patients (p < 0.001).
• AQI demonstrated superior classification accuracy (0.93 training, 0.85 testing) compared to SUVR (0.88 training, 0.83 testing) and DVR (0.89 training, 0.84 testing).
• AQI showed the largest effect size (2.35) and correctly identified some cases missed by SUVR/DVR, correlating well with clinical scores.

Conclusions:

• AQI effectively combines early kinetic and deposition information from a 30-minute scan for improved AD differentiation.
• AQI offers a more efficient and potentially more sensitive diagnostic approach for Alzheimer's disease.
• This novel index may help identify clinically ambiguous AD cases based on ¹¹C-PiB retention.