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Updated: Jun 24, 2025
Hybrid PET/MRI Imaging of Alzheimer's Disease Based on 18F-AV-1451
Published on: April 18, 2025
Postmortem imaging reveals patterns of medial temporal lobe vulnerability to tau pathology in Alzheimer's disease
Sadhana Ravikumar1, Amanda E Denning2, Sydney Lim2
1Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA. sadhana.ravikumar@gmail.com.
Abstract:
Our current understanding of the spread and neurodegenerative effects of tau neurofibrillary tangles (NFTs) within the medial temporal lobe (MTL) during the early stages of Alzheimer's Disease (AD) is limited by the presence of confounding non-AD pathologies and the two-dimensional (2-D) nature of conventional histology studies. Here, we combine ex vivo MRI and serial histological imaging from 25 human MTL specimens to present a detailed, 3-D characterization of quantitative NFT burden measures in the space of a high-resolution, ex vivo atlas with cytoarchitecturally-defined subregion labels, that can be used to inform future in vivo neuroimaging studies. Average maps show a clear anterior to poster gradient in NFT distribution and a precise, spatial pattern with highest levels of NFTs found not just within the transentorhinal region but also the cornu ammonis (CA1) subfield. Additionally, we identify granular MTL regions where measures of neurodegeneration are likely to be linked to NFTs specifically, and thus potentially more sensitive as early AD biomarkers.
Insights
This study provides a 3D map of tau neurofibrillary tangles (NFTs) in the medial temporal lobe (MTL) during early Alzheimer's Disease (AD). Findings reveal specific MTL regions with high NFT burden, potentially improving early AD biomarker detection.
Area of Science:
- Neuroscience
- Neuropathology
- Medical Imaging
Background:
- Understanding tau neurofibrillary tangle (NFT) spread in early Alzheimer's Disease (AD) is challenging due to confounding pathologies and 2D histology.
- The medial temporal lobe (MTL) is critical in early AD, but detailed 3D mapping of NFTs is lacking.
Purpose of the Study:
- To create a detailed 3D characterization of quantitative NFT burden in human MTL specimens.
- To develop a high-resolution ex vivo atlas with cytoarchitecturally-defined subregions for NFT analysis.
- To inform future in vivo neuroimaging studies for early AD detection.
Main Methods:
- Combined ex vivo MRI and serial histological imaging from 25 human MTL specimens.
- Developed a 3D atlas with precise subregion labels for quantitative NFT burden mapping.
- Analyzed spatial distribution and gradient of NFTs within MTL subregions.
Main Results:
- Demonstrated a clear anterior-to-posterior gradient in NFT distribution within the MTL.
- Identified specific spatial patterns of high NFT burden in the transentorhinal region and the cornu ammonis (CA1) subfield.
- Located granular MTL regions where neurodegeneration is specifically linked to NFTs, suggesting potential early AD biomarkers.
Conclusions:
- The 3D characterization provides a novel understanding of tau pathology spread in the early stages of AD.
- The identified MTL regions with high NFT burden and specific neurodegeneration links can guide the development of more sensitive early AD biomarkers.
- This approach enhances the potential for improved in vivo neuroimaging analysis in Alzheimer's Disease research.
