Modified RCTU Score: A Semi-Quantitative, Visual Tool for Predicting Alzheimer's Conversion from aMCI

Area of Science:

• Neurology
• Nuclear Medicine
• Neuroimaging

Background:

• Mild Cognitive Impairment (MCI) is a prodromal stage for Alzheimer's Disease (AD).
• Early prediction of AD conversion from MCI is crucial for timely intervention.
• Amyloid Positron Emission Tomography (PET) is a key biomarker for AD pathology.

Purpose of the Study:

• To evaluate a modified Regional Cerebrospinal Tau Uptake (RCTU) score derived from amyloid PET scans.
• To assess the modified RCTU score's ability to predict the progression from amnestic MCI (aMCI) to AD.
• To compare the modified RCTU score with the conventional RCTU score and amyloid Standardized Uptake Value Ratio (SUVR).

Main Methods:

• Retrospective analysis of 45 aMCI patients with baseline amyloid PET scans.
• Modification of the RCTU score by segmenting cerebral lobes into seven distinct regions.
• Correlation analysis between modified RCTU scores, conventional RCTU scores, and amyloid SUVR.
• Neuropsychological testing to identify conversion to AD during follow-up.

Main Results:

• 12 out of 45 patients progressed to AD over 17.8 ± 6.8 months.
• AD converters exhibited significantly higher modified RCTU scores compared to non-converters.
• The modified RCTU score demonstrated a strong correlation with amyloid SUVR (r > 0.7).
• Symmetric amyloid deposition, identified by the modified RCTU, was associated with a higher risk of AD conversion.

Conclusions:

• The modified RCTU score is a promising tool for predicting AD conversion in aMCI patients.
• The modified RCTU score accurately reflects amyloid burden and its distribution, including asymmetry.
• Symmetric amyloid deposition patterns identified by the modified RCTU score are indicative of increased AD progression risk.