Dataset Information

¹⁸F-Flortaucipir PET/MRI Correlations in Nonamnestic and Amnestic Variants of Alzheimer Disease.

ABSTRACT: Nonamnestic Alzheimer disease (AD) variants, including posterior cortical atrophy and the logopenic variant of primary progressive aphasia, differ from amnestic AD in distributions of tau aggregates and neurodegeneration. We evaluated whether ¹⁸F-flortaucipir (also called ¹⁸F-AV-1451) PET, targeting tau aggregates, detects these differences, and we compared the results with MRI measures of gray matter (GM) atrophy. Methods: Five subjects with posterior cortical atrophy, 4 subjects with the logopenic variant of primary progressive aphasia, 6 age-matched patients with AD, and 6 control subjects underwent ¹⁸F-flortaucipir PET and MRI. SUV ratios and GM volumes were compared using regional and voxel-based methods. Results: The subgroups showed the expected ¹⁸F-flortaucipir-binding patterns. Group effect sizes were generally stronger with ¹⁸F-flortaucipir PET than with MRI volumes. There were moderate-to-high correlations between regional GM atrophy and ¹⁸F-flortaucipir uptake. ¹⁸F-flortaucipir binding and GM atrophy correlated similarly to cognitive test performance. Conclusion:¹⁸F-flortaucipir binding corresponds to the expected neurodegeneration patterns in nonamnestic AD, with potential for earlier detection of pathology than is possible with MRI atrophy measures.

SUBMITTER: Nasrallah IM

PROVIDER: S-EPMC6348438 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature

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18F-Flortaucipir PET/MRI Correlations in Nonamnestic and Amnestic Variants of Alzheimer Disease.

Nasrallah Ilya M IM Chen Yin Jie YJ Hsieh Meng-Kang MK Phillips Jeffrey S JS Ternes Kylie K Stockbower Grace E GE Sheline Yvette Y McMillan Corey T CT Grossman Murray M Wolk David A DA

Journal of nuclear medicine : official publication, Society of Nuclear Medicine 20170726 2

Nonamnestic Alzheimer disease (AD) variants, including posterior cortical atrophy and the logopenic variant of primary progressive aphasia, differ from amnestic AD in distributions of tau aggregates and neurodegeneration. We evaluated whether 18F-flortaucipir (also called 18F-AV-1451) PET, targeting tau aggregates, detects these differences, and we compared the results with MRI measures of gray matter (GM) atrophy. Methods: Five subjects with posterior cortical atrop ...[more]

PMID: 28747523

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Project description:This study aimed to determine the pattern of [18F]flortaucipir uptake in individuals affected by Gerstmann-Sträussler-Scheinker disease (GSS) associated with the PRNP F198S mutation. The aims were to: 1) determine the pattern of [18F]flortaucipir uptake in two GSS patients; 2) compare tau distribution by [18F]flortaucipir PET imaging among three groups: two GSS patients, two early onset Alzheimer's disease patients (EOAD), two cognitively normal older adults (CN); 3) validate the PET imaging by comparing the pattern of [18F]flortaucipir uptake, in vivo, with that of tau neuropathology, post-mortem. Scans were processed to generate standardized uptake value ratio (SUVR) images. Regional [18F]flortaucipir SUVR was extracted and compared between GSS patients, EOADs, and CNs. Neuropathology and tau immunohistochemistry were carried out post-mortem on a GSS patient who died 9 months after the [18F]flortaucipir scan. The GSS patients were at different stages of disease progression. Patient A was mildly to moderately affected, suffering from cognitive, psychiatric, and ataxia symptoms. Patient B was moderately to severely affected, suffering from ataxia and parkinsonism accompanied by psychiatric and cognitive symptoms. The [18F]flortaucipir scans showed uptake in frontal, cingulate, and insular cortices, as well as in the striatum and thalamus. Uptake was greater in Patient B than in Patient A. Both GSS patients showed greater uptake in the striatum and thalamus than the EOADs and greater uptake in all evaluated regions than the CNs. Thioflavin S fluorescence and immunohistochemistry revealed that the anatomical distribution of tau pathology is consistent with that of [18F]flortaucipir uptake. In GSS patients, the neuroanatomical localization of pathologic tau, as detected by [18F]flortaucipir, suggests correlation with the psychiatric, motor, and cognitive symptoms. The topography of uptake in PRNP F198S GSS is strikingly different from that seen in AD. Further studies of the sensitivity, specificity, and anatomical patterns of tau PET in diseases with tau pathology are warranted.

Project description:BackgroundThe tau positron emission tomography (PET) ligand 18F-flortaucipir binds to paired helical filaments of tau in aging and Alzheimer's disease (AD), but its utility in detecting tau aggregates in frontotemporal dementia (FTD) is uncertain.MethodsWe performed 18F-flortaucipir imaging in patients with the FTD syndromes (n = 45): nonfluent variant primary progressive aphasia (nfvPPA) (n = 11), corticobasal syndrome (CBS) (n = 10), behavioral variant frontotemporal dementia (bvFTD) (n = 10), semantic variant primary progressive aphasia (svPPA) (n = 2) and FTD associated pathogenic genetic mutations microtubule-associated protein tau (MAPT) (n = 6), chromosome 9 open reading frame 72 (C9ORF72) (n = 5), and progranulin (GRN) (n = 1). All patients underwent MRI and β-amyloid biomarker testing via 11C-PiB or cerebrospinal fluid. 18F-flortaucipir uptake in patients was compared to 53 β-amyloid negative normal controls using voxelwise and pre-specified region of interest approaches.ResultsOn qualitative assessment, patients with nfvPPA showed elevated 18F-flortacupir binding in the left greater than right inferior frontal gyrus. Patients with CBS showed elevated binding in frontal white matter, with higher cortical gray matter uptake in a subset of β-amyloid-positive patients. Five of ten patients with sporadic bvFTD demonstrated increased frontotemporal binding. MAPT mutation carriers had elevated 18F-flortaucipir retention primarily, but not exclusively, in mutations with Alzheimer's-like neurofibrillary tangles. However, tracer retention was also seen in patients with svPPA, and the mutations C9ORF72, GRN predicted to have TDP-43 pathology. Quantitative region-of-interest differences between patients and controls were seen only in inferior frontal gyrus in nfvPPA and left insula and bilateral temporal poles in MAPT carriers. No significant regional differences were found in CBS or sporadic bvFTD. Two patients underwent postmortem neuropathological examination. A patient with C9ORF72, TDP-43-type B pathology, and incidental co-pathology of scattered neurofibrillary tangles in the middle frontal, inferior temporal gyrus showed corresponding mild 18F-flortaucipir retention without additional uptake matching the widespread TDP-43 type B pathology. A patient with sporadic bvFTD demonstrated punctate inferior temporal and hippocampus tracer retention, corresponding to the area of severe argyrophilic grain disease pathology.Conclusions18F-flortaucipir in patients with FTD and predicted tauopathy or TDP-43 pathology demonstrated limited sensitivity and specificity. Further postmortem pathological confirmation and development of FTD tau-specific ligands are needed.

Project description:PurposeIn vivo Alzheimer's disease (AD) biomarkers for tau pathology are cerebrospinal fluid (CSF) phosphorylated tau (p-tau) and [18F]flortaucipir positron emission tomography (PET). Our aim was to assess associations between CSF p-tau with [18F]flortaucipir PET and the associations of both tau biomarkers with cognition and atrophy.MethodsWe included 78 amyloid positive cognitively impaired patients (clinical diagnoses mild cognitive impairment (MCI, n = 8) and AD dementia (n = 45) and 25 cognitively normal subjects with subjective cognitive decline (SCD) (40% amyloid-positive)). Dynamic 130 min [18F]flortaucipir PET scans were acquired to generate binding potential (BPND) images using receptor parametric mapping and standardized uptake values ratios of 80-100 min (SUVr80-100min) post injection. We obtained regional BPND and SUVr from entorhinal, limbic, and neocortical regions-of-interest (ROIs), closely aligning to the neuropathological tau staging schemes. Cognition was assessed using MMSE and composite scores of four cognitive domains, and atrophy was measured using gray matter volume covering the major brain lobes. First, we used linear regressions to investigate associations between CSF p-tau (independent variable) and tau PET (dependent variable). Second, we used linear regressions to investigate associations between CSF p-tau, tau PET (separate independent variables, model 1), and cognition (dependent variable). We then assessed the independent effects of CSF p-tau and tau PET on cognition by simultaneously adding the other tau biomarker as a predictor (model 2). Finally, we performed the same procedure for model 1 and 2, but replaced cognition with atrophy. Models were adjusted for age, sex, time lag between assessments, education (cognition only), and total intracranial volume (atrophy only).ResultsHigher [18F]flortaucipir BPND was associated with higher CSF p-tau (range of standardized betas (sβ) across ROIs, 0.43-0.46; all p < 0.01). [18F]flortaucipir BPND was more strongly associated with cognition and atrophy than CSF p-tau. When [18F]flortaucipir BPND and CSF p-tau were entered simultaneously, [18F]flortaucipir BPND (range sβ = - 0.20 to - 0.57, all p < 0.05) was strongly associated with multiple cognitive domains and atrophy regions. SUVr showed comparable results to BPND.ConclusionRegional [18F]flortaucipir BPND correlated stronger with cognition and neurodegeneration than CSF p-tau, suggesting that tau PET more accurately reflects disease severity in AD.

Dataset Information

¹⁸F-Flortaucipir PET/MRI Correlations in Nonamnestic and Amnestic Variants of Alzheimer Disease.

Publications

<sup>18</sup>F-Flortaucipir PET/MRI Correlations in Nonamnestic and Amnestic Variants of Alzheimer Disease.

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