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- Leinonen, V., et al.
(författare)
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S- F-18 THK-5117-PET and C-11 PIB-PET Imaging in Idiopathic Normal Pressure Hydrocephalus in Relation to Confirmed Amyloid-beta Plaques and Tau in Brain Biopsies
- 2018
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Ingår i: Journal of Alzheimers Disease. - : IOS Press. - 1387-2877 .- 1875-8908. ; 64:1, s. 171-179
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Tidskriftsartikel (refereegranskat)abstract
- Background: Detection of pathological tau aggregates could facilitate clinical diagnosis of Alzheimer's disease (AD) and monitor drug effects in clinical trials. S-[F-18] THK-5117 could be a potential tracer to detect pathological tau deposits in brain. However, no previous study have correlated S-[F-18] THK-5117 uptake in PET with brain biopsy verified tau pathology in vivo. Objective: Here we aim to evaluate the association between cerebrospinal fluid (CSF) AD biomarkers, S-[F-18] THK-5117, and [C-11] PIB PET against tau and amyloid lesions in brain biopsy. Methods: Fourteen patients with idiopathic normal pressure hydrocephalus (iNPH) with previous shunt surgery including right frontal cortical brain biopsy and CSF A beta(1-42), total tau, and P-tau(181) measures, underwent brain MRI, [C-11] PIB PET, and S-[F-18] THK-5117 PET imaging. Results: Seven patients had amyloid-beta(A beta, 4G8) plaques, two both A beta and phosphorylated tau (P tau, AT8) and one only P tau in biopsy. As expected, increased brain biopsy A beta was well associated with higher [C-11] PIB uptake in PET. However, S-[F-18] THK-5117 uptake did not show any statistically significant correlation with either brain biopsy P tau or CSF P-tau(181) or total tau. Conclusions: S-[F-18] THK-5117 lacked clear association with neuropathologically verified tau pathology in brain biopsy probably, at least partially, due to off-target binding. Further studies with larger samples of patients with different tau tracers are urgently needed. The detection of simultaneous A beta and tau pathology in iNPH is important since that may indicate poorer and especially shorter response for CSF shunt surgery compared with no pathology.
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| 3. |
- Oliveira, F., et al.
(författare)
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Data driven diagnostic classification in Alzheimer's disease based on different reference regions for normalization of PiB-PET images and correlation with CSF concentrations of A beta species
- 2018
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Ingår i: Neuroimage-Clinical. - : Elsevier BV. - 2213-1582. ; 20, s. 603-610
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Tidskriftsartikel (refereegranskat)abstract
- Positron emission tomography (PET) neuroimaging with the Pittsburgh Compound_B (PiB) is widely used to assess amyloid plaque burden. Standard quantification approaches normalize PiB-PET by mean cerebellar gray matter uptake. Previous studies suggested similar pons and white-matter uptake in Alzheimer's disease (AD) and healthy controls (HC), but lack exhaustive comparison of normalization across the three regions, with data-driven diagnostic classification. We aimed to compare the impact of distinct reference regions in normalization, measured by data-driven statistical analysis, and correlation with cerebrospinal fluid (CSF) amyloid beta (A beta) species concentrations. 243 individuals with clinical diagnosis of AD, HC, mild cognitive impairment (MCI) and other dementias, from the Biomarkers for Alzheimer's/Parkinson's Disease (BIOMARKAPD) initiative were included. PiB-PET images and CSF concentrations of A beta(38), A beta(40) and A beta(42) were submitted to classification using support vector machines. Voxel-wise group differences and correlations between normalized PiB-PET images and CSF A beta concentrations were calculated. Normalization by cerebellar gray matter and pons yielded identical classification accuracy of AD (accuracy-96%, sensitivity-96%, specificity-95%), and significantly higher than A beta concentrations (best accuracy 91%). Normalization by the white-matter showed decreased extent of statistically significant multivoxel patterns and was the only method not outperforming CSF biomarkers, suggesting statistical inferiority. A beta(38) and A beta(40) correlated negatively with PiB-PET images normalized by the white-matter, corroborating previous observations of correlations with non-AD-specific subcortical changes in white-matter. In general, when using the pons as reference region, higher voxel-wise group differences and stronger correlation with A beta(42), the A beta(42)/A beta(40) or A beta(42)/A beta(38) ratios were found compared to normalization based on cerebellar gray matter.
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