| 1. |
- Jonasson, My, et al.
(författare)
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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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Ingår i: NeuroImage. - : Elsevier BV. - 2213-1582. ; 22
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Tidskriftsartikel (refereegranskat)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.
(författare)
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Clinical impact of [18F]flutemetamol PET among memory clinic patients with an unclear diagnosis.
- 2019
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Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 46:6, s. 1276-1286
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To investigate the impact of amyloid PET with [18F]flutemetamol on diagnosis and treatment management in a cohort of patients attending a tertiary memory clinic in whom, despite extensive cognitive assessment including neuropsychological testing, structural imaging, CSF biomarker analysis and in some cases [18F]FDG PET, the diagnosis remained unclear.METHODS: The study population consisted of 207 patients with a clinical diagnosis prior to [18F]flutemetamol PET including mild cognitive impairment (MCI; n = 131), Alzheimer's disease (AD; n = 41), non-AD (n = 10), dementia not otherwise specified (dementia NOS; n = 20) and subjective cognitive decline (SCD; n = 5).RESULTS: Amyloid positivity was found in 53% of MCI, 68% of AD, 20% of non-AD, 20% of dementia NOS, and 60% of SCD patients. [18F]Flutemetamol PET led, overall, to a change in diagnosis in 92 of the 207 patients (44%). A high percentage of patients with a change in diagnosis was observed in the MCI group (n = 67, 51%) and in the dementia NOS group (n = 11; 55%), followed by the non-AD and AD (30% and 20%, respectively). A significant increase in cholinesterase inhibitor treatment was observed after [18F]flutemetamol PET (+218%, 34 patients before and 108 patients after).CONCLUSION: The present study lends support to the clinical value of amyloid PET in patients with an uncertain diagnosis in the tertiary memory clinic setting.
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| 3. |
- Leuzy, Antoine, et al.
(författare)
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Tau PET imaging in neurodegenerative tauopathies-still a challenge
- 2019
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Ingår i: Molecular Psychiatry. - : Springer Science and Business Media LLC. - 1359-4184 .- 1476-5578. ; 24:8, s. 1112-1134
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Forskningsöversikt (refereegranskat)abstract
- The accumulation of pathological misfolded tau is a feature common to a collective of neurodegenerative disorders known as tauopathies, of which Alzheimer's disease (AD) is the most common. Related tauopathies include progressive supranuclear palsy (PSP), corticobasal syndrome (CBS), Down's syndrome (DS), Parkinson's disease (PD), and dementia with Lewy bodies (DLB). Investigation of the role of tau pathology in the onset and progression of these disorders is now possible due the recent advent of tau-specific ligands for use with positron emission tomography (PET), including first-(e.g., [F-18] THK5317, [F-18] THK5351, [F-18] AV1451, and [C-11] PBB3) and second-generation compounds [namely [F-18] MK-6240, [F-18] RO-948 (previously referred to as [F-18] RO69558948), [F-18] PI-2620, [F-18] GTP1, [F-18] PM-PBB3, and [F-18] JNJ64349311 ([F-18] JNJ311) and its derivative [F-18] JNJ-067)]. In this review we describe and discuss findings from in vitro and in vivo studies using both initial and new tau ligands, including their relation to biomarkers for amyloid-beta and neurodegeneration, and cognitive findings. Lastly, methodological considerations for the quantification of in vivo ligand binding are addressed, along with potential future applications of tau PET, including therapeutic trials.
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| 4. |
- Lilja, Johan, et al.
(författare)
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Spatial normalization of 18F-Flutemetamol PET images using an adaptive principal-component template
- 2019
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 60:2, s. 285-291
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Tidskriftsartikel (refereegranskat)abstract
- Though currently approved for visual assessment only, there is evidence to suggest that quantification of amyloid-β (Aβ) PET images may reduce interreader variability and aid in the monitoring of treatment effects in clinical trials. Quantification typically involves a regional atlas in standard space, requiring PET images to be spatially normalized. Different uptake patterns in Aβ-positive and Aβ-negative subjects, however, make spatial normalization challenging. In this study, we proposed a method to spatially normalize 18F-flutemetamol images using a synthetic template based on principal-component images to overcome these challenges.Methods: 18F-flutemetamol PET and corresponding MR images from a phase II trial (n = 70), including subjects ranging from Aβ-negative to Aβ-positive, were spatially normalized to standard space using an MR-driven registration method (SPM12). 18F-flutemetamol images were then intensity-normalized using the pons as a reference region. Principal-component images were calculated from the intensity-normalized images. A linear combination of the first 2 principal-component images was then used to model a synthetic template spanning the whole range from Aβ-negative to Aβ-positive. The synthetic template was then incorporated into our registration method, by which the optimal template was calculated as part of the registration process, providing a PET-only–driven registration method. Evaluation of the method was done in 2 steps. First, coregistered gray matter masks generated using SPM12 were spatially normalized using the PET- and MR-driven methods, respectively. The spatially normalized gray matter masks were then visually inspected and quantified. Second, to quantitatively compare the 2 registration methods, additional data from an ongoing study were spatially normalized using both methods, with correlation analysis done on the resulting cortical SUV ratios.Results: All scans were successfully spatially normalized using the proposed method with no manual adjustments performed. Both visual and quantitative comparison between the PET- and MR-driven methods showed high agreement in cortical regions. 18F-flutemetamol quantification showed strong agreement between the SUV ratios for the PET- and MR-driven methods (R2 = 0.996; pons reference region).Conclusion: The principal-component template registration method allows for robust and accurate registration of 18F-flutemetamol images to a standardized template space, without the need for an MR image.
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| 5. |
- Natarajan Arul, Murugan, et al.
(författare)
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Cross-interaction of tau PET tracers with monoamine oxidase B : evidence from in silico modelling and in vivo imaging
- 2019
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Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer. - 1619-7070 .- 1619-7089. ; 46:6, s. 1369-1382
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Tidskriftsartikel (refereegranskat)abstract
- PurposeSeveral tracers have been designed for tracking the abnormal accumulation of tau pathology in vivo. Recently, concerns have been raised about the sources of off-target binding for these tracers; inconclusive data propose binding for some tracers to monoamine oxidase B (MAO-B).MethodsMolecular docking and dynamics simulations were used to estimate the affinity and free energy for the binding of several tau tracers (FDDNP, THK523, THK5105, THK5317, THK5351, T807 [aka AV-1451, flortaucipir], T808, PBB3, RO-948, MK-6240, JNJ-311 and PI-2620) to MAO-B. These values were then compared with those for safinamide (MAO-B inhibitor). PET imaging was used with the tau tracer [F-18]THK5317 and the MAO-B tracer [C-11]DED in five patients with Alzheimer's disease to investigate the MAO-B binding component of this first generation tau tracer in vivo.ResultsThe computational modelling studies identified a binding site for all the tau tracers on MAO-B; this was the same site as that for safinamide. The binding affinity and free energy of binding for the tau tracers to MAO-B was substantial and in a similar range to those for safinamide. The most recently developed tau tracers MK-6240, JNJ-311 and PI-2620 appeared, in silico, to have the lowest relative affinity for MAO-B. The in vivo investigations found that the regional distribution of binding for [F-18]THK5317 was different from that for [C-11]DED, although areas of suspected off-target [F-18]THK5317 binding were detected. The binding relationship between [F-18]THK5317 and [C-11]DED depended on the availability of the MAO-B enzyme.ConclusionsThe developed tau tracers show in silico and in vivo evidence of cross-interaction with MAO-B; the MAO-B component of the tracer binding was dependent on the regional concentration of the enzyme.
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