| 1. |
- Jonasson, My, et al.
(author)
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Optimal timing of tau pathology imaging and automatic extraction of a reference region using dynamic [18F]THK5317 PET
- 2019
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In: NeuroImage. - : Elsevier BV. - 2213-1582. ; 22
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Journal article (peer-reviewed)abstract
- [F-18]THK5317 is a PET tracer for in-vivo imaging of tau associated with Alzheimer's disease (AD). This work aimed to evaluate optimal timing for standardized uptake value ratio (SUVR) measures with [F-18]THK5317 and automated generation of SUVR-1 and relative cerebral blood flow (R-1) parametric images. Nine AD patients and nine controls underwent 90 min [F-18]THK5317 scans. SUVR-1 was calculated at transient equilibrium (TE) and for seven different 20 min intervals and compared with distribution volume ratio (DVR; reference Logan). Cerebellar grey matter (MRI) was used as reference region. A supervised cluster analysis (SVCA) method was implemented to automatically generate a reference region, directly from the dynamic PET volume without the need of a structural MRI scan, for computation of SUVR-1 and R-1 images for a scan duration matching the optimal timing. TE was reached first in putamen, frontal- and parietal cortex at 22 +/- 4 min for AD patients and in putamen at 20 +/- 0 min in controls. Over all regions and subjects, SUVR20-40-1 correlated best with DVR-1, R-2 = 0.97. High correlation was found between values generated using MRI- and SVCA-based reference (R-2 = 0.93 for SUVR20-40-1; R-2 = 0.94 for R-1). SUVR20-40 allows for accurate semi-quantitative assessment of tau pathology and SVCA may be used to obtain a reference region for calculation of both SUVR-1 and R-1 with 40 min scan duration.
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| 2. |
- Leuzy, Antoine, et al.
(author)
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Concordance and Diagnostic Accuracy of [C-11]PIB PET and Cerebrospinal Fluid Biomarkers in a Sample of Patients with Mild Cognitive Impairment and Alzheimer's Disease
- 2015
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In: Journal of Alzheimer's Disease. - 1387-2877 .- 1875-8908. ; 45:4, s. 1077-1088
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Journal article (peer-reviewed)abstract
- Background: Alzheimer's disease (AD) pathology can be quantified in vivo using cerebrospinal fluid (CSF) levels of amyloid-beta(1-42) (A beta(1-42)), total-tau (t-tau), and phosphorylated tau (p- tau(181p)), as well as with positron emission tomography (PET) using [C-11]Pittsburgh compound-B ([C-11]PIB). Studies assessing concordance between these measures, however, have provided conflicting results. Moreover, it has been proposed that [C-11]PIB PET may be of greater clinical utility in terms of identifying patients with mild cognitive impairment (MCI) who will progress to the dementia phase of AD. Objective: To determine concordance and classification accuracy of CSF biomarkers and [C-11]PIB PET in a cohort of patients with MCI and AD. Methods: 68 patients (MCI, n = 33; AD, n = 35) underwent [C-11]PIB PET and CSF sampling. Cutoffs of >1.41 ([C-11]PIB), <450 pg/mL-and a more lenient cutoff of 550 pg/mL-(A beta(1-42)), <6.5 (A beta(1-42)/p-tau181p), and 1.14 (A beta(1- 42)/t-tau), were used to determine concordance. Logistic regression was used to determine classification accuracy with respect to stable MCI (sMCI) versus MCI who progressed to AD (pMCI). Results: Concordance between [C-11]PIB and A beta(1-42) was highest for sMCI (67%), followed by AD (60%) and pMCI (33%). Agreement was increased across groups using A beta(1-42) < 550 pg/mL, or A beta(1-42) to tau ratios. Logistic regression showed that classification accuracy of [11C] PIB, between sMCI and pMCI, was superior to A beta(1-42) (73% versus 58%), A beta(1-42)/t-tau (63%), and A beta(1-42)/p-tau181p (65%). Conclusion: In the present study, [C-11]PIB proved a better predictor of progression to AD in patients with MCI, relative to CSF measures of A beta(1-42) or A beta(1-42)/tau. Discordance between PET and CSF markers for A beta(1-42) suggests they cannot be used interchangeably, as is currently the case.
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| 3. |
- Leuzy, Antoine, et al.
(author)
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Longitudinal uncoupling of cerebral perfusion, glucose metabolism, and tau deposition in Alzheimer's disease
- 2018
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In: Alzheimer's & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 14:5, s. 652-663
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Journal article (peer-reviewed)abstract
- Introduction: Cross-sectional findings using the tau tracer [F-18] THK5317 (THK5317) have shown that [F-18]fluorodeoxyglucose (FDG) positron emission tomography (PET) data can be approximated using perfusion measures (early-frame standardized uptake value ratio; ratio of tracer delivery in target to reference regions). In this way, a single PET study can provide both functional and molecular information. Methods: We included 16 patients with Alzheimer's disease who completed follow-up THK5317 and FDG studies 17 months after baseline investigations. Linear mixed-effects models and annual percentage change maps were used to examine longitudinal change. Results: Limited spatial overlap was observed between areas showing declines in THK5317 perfusion measures and FDG. Minimal overlap was seen between areas showing functional change and those showing increased retention of THK5317. Discussion: Our findings suggest a spatiotemporal offset between functional changes and tau pathology and a partial uncoupling between perfusion and metabolism, possibly as a function of Alzheimer's disease severity.
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| 4. |
- Rodriguez-Vieitez, Elena, et al.
(author)
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Comparability of [F-18]THK5317 and [C-11]PIB blood flow proxy images with [F-18]FDG positron emission tomography in Alzheimer's disease
- 2017
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In: Journal of Cerebral Blood Flow and Metabolism. - : SAGE PUBLICATIONS INC. - 0271-678X .- 1559-7016. ; 37:2, s. 740-749
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Journal article (peer-reviewed)abstract
- For amyloid positron emission tomography tracers, the simplified reference tissue model derived ratio of influx rate in target relative to reference region (R-1) has been shown to serve as a marker of brain perfusion, and, due to the strong coupling between perfusion and metabolism, as a proxy for glucose metabolism. In the present study, 11 prodromal Alzheimer's disease and nine Alzheimer's disease dementia patients underwent [F-18]THK5317, carbon-11 Pittsburgh Compound-B ([C-11]PIB), and 2-deoxy-2-[F-18]fluoro-D-glucose ([F-18]FDG) positron emission tomography to assess the possible use of early-phase [F-18]THK5317 and R-1 as proxies for brain perfusion, and thus, for glucose metabolism. Discriminative performance (prodromal vs Alzheimer's disease dementia) of [F-18]THK5317 (early-phase SUVr and R-1) was compared with that of [C-11]PIB (early-phase SUVr and R-1) and [F-18]FDG. Strong positive correlations were found between [F-18]THK5317 (early-phase, R-1) and [F-18]FDG, particularly in frontal and temporoparietal regions. Differences in correlations between early-phase and R-1 ([F-18]THK5317 and [C-11]PIB) and [F-18]FDG, were not statistically significant, nor were differences in area under the curve values in the discriminative analysis. Our findings suggest that early-phase [F-18]THK5317 and R-1 provide information on brain perfusion, closely related to glucose metabolism. As such, a single positron emission tomography study with [F-18]THK5317 may provide information about both tau pathology and brain perfusion in Alzheimer's disease, with potential clinical applications.
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| 5. |
- Rodriguez-Vieitez, Elena, et al.
(author)
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Comparison of Early-Phase C-11-Deuterium-L-Deprenyl and C-11-Pittsburgh Compound B PET for Assessing Brain Perfusion in Alzheimer Disease
- 2016
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In: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 57:7, s. 1071-1077
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Journal article (peer-reviewed)abstract
- The PET tracer C-11-deuterium-L-deprenyl (C-11-DED) has been used to visualize activated astrocytes in vivo in patients with Alzheimer disease (AD). In this multitracer PET study, early-phase C-11-DED and C-11-Pittsburgh compound B (C-11-PiB) (eDED and ePiB, respectively) were compared as surrogate markers of brain perfusion, and the extent to which C-11-DED binding is influenced by brain perfusion was investigated. METHODS: C-11-DED, C-11-PiB, and F-18-FDG dynamic PET scans were obtained in age-matched groups comprising AD patients (n = 8), patients with mild cognitive impairment (n = 17), and healthy controls (n = 16). A modified reference Patlak model was used to quantify C-11-DED binding. A simplified reference tissue model was applied to both C-11-DED and C-11-PiB to measure brain perfusion relative to the cerebellar gray matter (R-1) and binding potentials. C-11-PiB retention and F-18-FDG uptake were also quantified as target-to-pons SUV ratios in 12 regions of interest (ROIs). RESULTS: The strongest within-subject correlations with the corresponding R-1 values (R-1,R-DED and R-1,R-PiB, respectively) and with F-18-FDG uptake were obtained when the eDED and ePiB PET data were measured 1-4 min after injection. The optimum eDED/ePiB intervals also showed strong, significant ROI-based intersubject Pearson correlations with R-1,R-DED/R-1,R-PiB and with F-18-FDG uptake, whereas C-11-DED binding was largely independent of brain perfusion, as measured by eDED. Corresponding voxelwise correlations confirmed the ROI-based results. Temporoparietal eDED or ePiB brain perfusion measurements were highly discriminative between patient and control groups, with discriminative ability statistically comparable to that of temporoparietal F-18-FDG glucose metabolism. Hypometabolism extended over wider regions than hypoperfusion in patient groups compared with controls. CONCLUSION: The 1- to 4-min early-frame intervals of C-11-DED or C-11-PiB are suitable surrogate measures for brain perfusion. C-11-DED binding is independent of brain perfusion, and thus C-11-DED PET can provide information on both functional (brain perfusion) and pathologic (astrocytosis) aspects from a single PET scan. In comparison with glucose metabolism, early-phase C-11-DED and C-11-PiB perfusion appear to provide complementary rather than redundant information.
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