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Updated: Dec 26, 2025
Hybrid PET/MRI Imaging of Alzheimer's Disease Based on 18F-AV-1451
Published on: April 18, 2025
Multiparametric imaging hippocampal neurodegeneration and functional connectivity with simultaneous PET/MRI in
Shaozhen Yan1,2,3, Chaojie Zheng2, Bixiao Cui4
1Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing, China.
Purpose:
The objective of this study is to investigate the hippocampal neurodegeneration and its associated aberrant functions in mild cognitive impairment (MCI) and Alzheimer's disease (AD) patients using simultaneous PET/MRI.
Methods:
Forty-two cognitively normal controls (NC), 38 MCI, and 22 AD patients were enrolled in this study. All subjects underwent 18F-FDG PET/functional MRI (fMRI) and high-resolution T1-weighted MRI scans on a hybrid GE Signa PET/MRI scanner. Neurodegeneration in hippocampus and its subregions was quantified by regional gray matter volume and 18F-FDG standardized uptake value ratio (SUVR) relative to cerebellum. An iterative reblurred Van Cittert iteration method was used for voxelwise partial volume correction on 18F-FDG PET images. Regional gray matter volume was estimated from voxel-based morphometric analysis with MRI. fMRI data were analyzed after slice time correction and head motion correction using statistical parametric mapping (SPM12) with DPARSF toolbox. The regions of interest including hippocampus, cornu ammonis (CA1), CA2/3/dentate gyrus (DG), and subiculum were defined in the standard MNI space.
Results:
Patient groups had reduced SUVR, gray matter volume, and functional connectivity compared to NC in CA1, CA2/3/DG, and subiculum (AD < MCI < NC). There was a linear correlation between the left CA2/3DG gray matter volume and 18F-FDG SUVR in AD patients (P < 0.001, r = 0.737). Significant correlation was also found between left CA2/3/DG-superior medial frontal gyrus functional connectivity and left CA2/3/DG hypometabolism in patients with AD. The functional connectivity of right CA1-precuneus in patients with MCI and right subiculum-superior frontal gyrus in patients with AD was positively correlated with mini mental status examination scores (P < 0.05).
Conclusion:
Our findings demonstrate that the associations existed at subregional hippocampal level between the functional connectivity measured by fMRI and neurodegeneration measured by structural MRI and 18F-FDG PET. Our results may provide a basis for precision neuroimaging of hippocampus in AD.
Insights
This study used PET/MRI to examine brain changes in mild cognitive impairment (MCI) and Alzheimer
Area of Science:
- Neuroimaging
- Neurodegeneration
- Alzheimer's Disease Research
Background:
- Mild cognitive impairment (MCI) and Alzheimer's disease (AD) are characterized by progressive neurodegeneration.
- Understanding the functional and structural brain changes in the hippocampus is crucial for early diagnosis and treatment.
- Simultaneous Positron Emission Tomography (PET) and Magnetic Resonance Imaging (MRI) offer advanced insights into brain function and structure.
Purpose of the Study:
- To investigate hippocampal neurodegeneration and its functional consequences in MCI and AD patients.
- To utilize simultaneous 18F-FDG PET/fMRI and structural MRI for comprehensive analysis.
- To correlate neuroimaging findings with cognitive status in patient cohorts.
Main Methods:
- Simultaneous 18F-FDG PET/fMRI and T1-weighted MRI scans were performed on 42 cognitively normal controls (NC), 38 MCI, and 22 AD patients.
- Neurodegeneration was quantified using regional gray matter volume (from MRI) and 18F-FDG standardized uptake value ratio (SUVR) (from PET).
- Functional connectivity was assessed using fMRI, with regions of interest including hippocampus subfields (CA1, CA2/3/DG, subiculum).
Main Results:
- MCI and AD groups showed reduced SUVR, gray matter volume, and functional connectivity in hippocampal subfields compared to NC (AD < MCI < NC).
- Significant linear correlations were found between gray matter volume and 18F-FDG SUVR in the left CA2/3DG of AD patients.
- Functional connectivity in specific hippocampal subfields correlated with hypometabolism in AD and with cognitive scores (MMSE) in MCI and AD patients.
Conclusions:
- Associations exist at the subregional hippocampal level between functional connectivity (fMRI) and neurodegeneration (MRI, PET).
- These findings highlight the utility of integrated neuroimaging for assessing hippocampal integrity in neurodegenerative diseases.
- The results may form a basis for precision neuroimaging strategies in Alzheimer's disease.
