Related Experiment Video
Updated: Jul 3, 2026
Hybrid PET/MRI Imaging of Alzheimer's Disease Based on 18F-AV-1451
Published on: April 18, 2025
Principal component analysis of FDG PET in amnestic MCI
Flavio Nobili1, Dario Salmaso, Silvia Morbelli
1Clinical Neurophysiology, Department of Endocrinological and Medical Sciences, University of Genoa, Genoa, Italy. flaviomariano.nobili@hsanmartino.it
Purpose:
The purpose of the study is to evaluate the combined accuracy of episodic memory performance and (18)F-FDG PET in identifying patients with amnestic mild cognitive impairment (aMCI) converting to Alzheimer's disease (AD), aMCI non-converters, and controls.
Methods:
Thirty-three patients with aMCI and 15 controls (CTR) were followed up for a mean of 21 months. Eleven patients developed AD (MCI/AD) and 22 remained with aMCI (MCI/MCI). (18)F-FDG PET volumetric regions of interest underwent principal component analysis (PCA) that identified 12 principal components (PC), expressed by coarse component scores (CCS). Discriminant analysis was performed using the significant PCs and episodic memory scores.
Results:
PCA highlighted relative hypometabolism in PC5, including bilateral posterior cingulate and left temporal pole, and in PC7, including the bilateral orbitofrontal cortex, both in MCI/MCI and MCI/AD vs CTR. PC5 itself plus PC12, including the left lateral frontal cortex (LFC: BAs 44, 45, 46, 47), were significantly different between MCI/AD and MCI/MCI. By a three-group discriminant analysis, CTR were more accurately identified by PET-CCS + delayed recall score (100%), MCI/MCI by PET-CCS + either immediate or delayed recall scores (91%), while MCI/AD was identified by PET-CCS alone (82%). PET increased by 25% the correct allocations achieved by memory scores, while memory scores increased by 15% the correct allocations achieved by PET.
Conclusion:
Combining memory performance and (18)F-FDG PET yielded a higher accuracy than each single tool in identifying CTR and MCI/MCI. The PC containing bilateral posterior cingulate and left temporal pole was the hallmark of MCI/MCI patients, while the PC including the left LFC was the hallmark of conversion to AD.
Insights
Combining memory tests and (18)F-FDG PET scans accurately identifies individuals with mild cognitive impairment (MCI) and those progressing to Alzheimer's disease (AD). This combined approach improves diagnostic accuracy for controls, MCI non-converters, and MCI converters.
Area of Science:
- Neuroimaging
- Neurology
- Cognitive Science
Background:
- Amnestic mild cognitive impairment (aMCI) is a transitional stage between normal aging and Alzheimer's disease (AD).
- Early and accurate identification of aMCI patients who will convert to AD is crucial for timely intervention.
- Current diagnostic methods, including memory assessments and neuroimaging, have limitations in predicting conversion.
Purpose of the Study:
- To evaluate the combined diagnostic accuracy of episodic memory performance and 18F-FDG PET scans.
- To differentiate between patients with aMCI who convert to AD (MCI/AD), aMCI who do not convert (MCI/MCI), and healthy controls (CTR).
Main Methods:
- Followed 33 aMCI patients and 15 controls for a mean of 21 months.
- Utilized 18F-FDG PET with principal component analysis (PCA) to identify patterns of hypometabolism.
- Performed discriminant analysis using PCA-derived component scores (CCS) and episodic memory test results.
Main Results:
- PCA identified hypometabolism in specific brain regions (posterior cingulate, temporal pole, orbitofrontal cortex) in both MCI/MCI and MCI/AD groups compared to controls.
- Distinct patterns of hypometabolism in the posterior cingulate/temporal pole (PC5) and left lateral frontal cortex (PC12) differentiated MCI/AD from MCI/MCI.
- Combined PET-CCS and memory scores achieved 100% accuracy for CTR, 91% for MCI/MCI, and 82% for MCI/AD.
- PET improved correct allocations by 25% compared to memory scores alone, and memory scores improved allocations by 15% compared to PET alone.
Conclusions:
- The combination of episodic memory testing and 18F-FDG PET significantly enhances diagnostic accuracy for CTR, MCI/MCI, and MCI/AD.
- Specific patterns of hypometabolism, particularly involving the posterior cingulate/temporal pole and left lateral frontal cortex, are key indicators.
- This multimodal approach offers a more robust method for identifying individuals at risk of AD progression.
