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MRI-Based Medial Temporal Atrophy May Reflect Amyloid PET Positivity in Cognitively Normal Individuals: A Preliminary
1Department of Psychiatry, ALZCLINIC TOKYO, Tokyo, JPN.
Abstract:
This study investigated whether magnetic resonance imaging (MRI)-based medial temporal morphometry can predict amyloid positron emission tomography (PET) positivity in cognitively normal individuals. Sixteen consecutive participants (eight amyloid PET-positive and eight PET-negative) were retrospectively identified, all within the normal cognitive range (Mini-Mental State Examination 28-30). Amyloid PET was performed using florbetapir, with visual interpretation as the primary diagnostic criterion and Centiloid values as supportive measures. MRI-derived volumetric analysis was conducted using the voxel-based specific regional analysis system for Alzheimer's disease (AD) to quantify medial temporal atrophy. Although between-group differences in hippocampal indices did not reach statistical significance, the PET-positive group showed a trend toward greater atrophy, and centiloid values correlated positively with medial temporal indices. Receiver operating characteristic analysis indicated fair discrimination, highest for the volume-of-interest-to-gray-matter ratio (area under the curve = 0.83). These preliminary findings suggest that subtle hippocampal alterations on routine structural MRI may mirror early amyloid pathology even before cognitive impairment, supporting the potential of MRI-based morphometric assessment as an adjunctive biomarker for early AD detection.
Insights
Magnetic resonance imaging (MRI) can detect early Alzheimer's disease (AD) changes. Subtle hippocampal atrophy on MRI may indicate amyloid PET positivity in cognitively normal individuals, aiding early AD detection.
Area of Science:
- Neuroimaging
- Alzheimer's Disease Research
Background:
- Early detection of Alzheimer's disease (AD) is crucial for timely intervention.
- Amyloid-beta (Aβ) deposition is an early pathological hallmark of AD.
- Cognitively normal individuals can harbor underlying AD pathology.
Purpose of the Study:
- To investigate if MRI-based medial temporal lobe morphometry predicts amyloid positron emission tomography (PET) positivity.
- To assess the utility of structural MRI as an early biomarker for AD pathology in cognitively normal individuals.
Main Methods:
- Retrospective analysis of 16 cognitively normal participants (8 amyloid PET-positive, 8 PET-negative).
- Amyloid PET using florbetapir with visual and Centiloid analysis.
- MRI-derived volumetric analysis of medial temporal atrophy using VSRAD.
- Receiver operating characteristic (ROC) analysis to evaluate diagnostic performance.
Main Results:
- The amyloid PET-positive group showed a trend towards greater medial temporal atrophy compared to the PET-negative group.
- Centiloid values positively correlated with medial temporal morphometric indices.
- The volume-of-interest-to-gray-matter ratio demonstrated fair diagnostic discrimination (AUC = 0.83).
Conclusions:
- Subtle hippocampal alterations on routine structural MRI may reflect early amyloid pathology in cognitively normal individuals.
- MRI-based morphometry shows potential as an adjunctive biomarker for early AD detection.
- These findings support the use of MRI in identifying individuals at risk for AD before significant cognitive decline.
