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Brain metabolic maps in Mild Cognitive Impairment predict heterogeneity of progression to dementia
Chiara Cerami1, Pasquale Anthony Della Rosa2, Giuseppe Magnani3
1Università Vita-Salute San Raffaele, Milan, Italy ; Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy ; Clinical Neuroscience Department, Neurorehabilitation Unit, San Raffaele Hospital, Milan, Italy.
Abstract:
[(18)F]FDG-PET imaging has been recognized as a crucial diagnostic marker in Mild Cognitive Impairment (MCI), supporting the presence or the exclusion of Alzheimer's Disease (AD) pathology. A clinical heterogeneity, however, underlies MCI definition. In this study, we aimed to evaluate the predictive role of single-subject voxel-based maps of [(18)F]FDG distribution generated through statistical parametric mapping (SPM) in the progression to different dementia subtypes in a sample of 45 MCI. Their scans were compared to a large normal reference dataset developed and validated for comparison at single-subject level. Additionally, Aβ42 and Tau CSF values were available in 34 MCI subjects. Clinical follow-up (mean 28.5 ± 7.8 months) assessed subsequent progression to AD or non-AD dementias. The SPM analysis showed: 1) normal brain metabolism in 14 MCI cases, none of them progressing to dementia; 2) the typical temporo-parietal pattern suggestive for prodromal AD in 15 cases, 11 of them progressing to AD; 3) brain hypometabolism suggestive of frontotemporal lobar degeneration (FTLD) subtypes in 7 and dementia with Lewy bodies (DLB) in 2 subjects (all fulfilled FTLD or DLB clinical criteria at follow-up); and 4) 7 MCI cases showed a selective unilateral or bilateral temporo-medial hypometabolism without the typical AD pattern, and they all remained stable. In our sample, objective voxel-based analysis of [(18)F]FDG-PET scans showed high predictive prognostic value, by identifying either normal brain metabolism or hypometabolic patterns suggestive of different underlying pathologies, as confirmed by progression at follow-up. These data support the potential usefulness of this SPM [(18)F]FDG PET analysis in the early dementia diagnosis and for improving subject selection in clinical trials based on MCI definition.
Insights
Statistical parametric mapping (SPM) analysis of [18F]FDG-PET scans accurately predicts dementia progression in mild cognitive impairment (MCI) patients. This method identifies normal metabolism or specific hypometabolic patterns, aiding early diagnosis and clinical trial selection.
Area of Science:
- Neuroimaging
- Neurology
- Nuclear Medicine
Background:
- Mild cognitive impairment (MCI) is clinically heterogeneous, complicating early diagnosis of underlying Alzheimer's Disease (AD) pathology.
- Fluorodeoxyglucose Positron Emission Tomography ([18F]FDG-PET) is a key imaging biomarker for AD in MCI.
- Predicting dementia subtype progression in MCI remains a challenge.
Purpose of the Study:
- To evaluate the predictive value of single-subject voxel-based [18F]FDG-PET maps using Statistical Parametric Mapping (SPM) for dementia progression in MCI.
- To differentiate between normal metabolism, AD, frontotemporal lobar degeneration (FTLD), and dementia with Lewy bodies (DLB) patterns in MCI.
- To assess the utility of SPM [18F]FDG-PET analysis for early dementia diagnosis and clinical trial subject selection.
Main Methods:
- Retrospective analysis of [18F]FDG-PET scans from 45 MCI subjects compared to a normal reference dataset.
- Voxel-based analysis using SPM to generate single-subject metabolic maps.
- Clinical follow-up (mean 28.5 months) to determine progression to AD or non-AD dementias.
- Cerebrospinal fluid (CSF) Aβ42 and Tau levels available for 34 subjects.
Main Results:
- 14 MCI cases showed normal metabolism and did not progress to dementia.
- 15 cases exhibited temporo-parietal hypometabolism suggestive of prodromal AD, with 11 progressing to AD.
- 10 cases showed hypometabolism indicative of FTLD (7) or DLB (2), and all progressed to respective diagnoses.
- 7 cases had stable temporo-medial hypometabolism without typical AD patterns, remaining stable.
Conclusions:
- Objective voxel-based [18F]FDG-PET analysis via SPM demonstrates high prognostic value in MCI.
- This method effectively identifies normal brain metabolism and specific hypometabolic patterns associated with different dementia pathologies.
- SPM [18F]FDG-PET analysis shows promise for early dementia diagnosis and optimizing MCI patient selection for clinical trials.
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