Abstract | PURPOSE: Recent research has suggested the use of white matter (WM) reference regions for longitudinal tau-PET imaging. However, tau tracers display affinity for the β-sheet structure formed by myelin, and thus WM lesions might influence tracer retention. Here, we explored whether the tau-sensitive tracer [ 18F]flortaucipir shows reduced retention in WM hyperintensities (WMH) and how this retention changes over time. METHODS: We included 707 participants from the Alzheimer's Disease Neuroimaging Initiative with available [ 18F]flortaucipir-PET and structural and FLAIR MRI scans. WM segments and WMH were automatically delineated in the structural MRI and FLAIR scans, respectively. [ 18F]flortaucipir standardized uptake value ratios (SUVR) of WMH and normal-appearing WM (NAWM) were calculated using the inferior cerebellar grey matter as reference region, and a 3-mm erosion was applied to the combined NAWM and WMH masks to avoid partial volume effects. Longitudinal [ 18F]flortaucipir SUVR changes in NAWM and WMH were estimated using linear mixed models. The percent variance of WM-referenced cortical [ 18F]flortaucipir SUVRs explained by longitudinal changes in the WM reference region was estimated with the R2 coefficient. RESULTS: Compared to NAWM, WMH areas displayed significantly reduced [ 18F]flortaucipir SUVR, independent of cognitive impairment or Aβ status (mean difference = 0.14 SUVR, p < 0.001). Older age was associated with lower [ 18F]flortaucipir SUVR in both NAWM (- 0.002 SUVR/year, p = 0.005) and WMH (- 0.004 SUVR/year, p < 0.001). Longitudinally, [ 18F]flortaucipir SUVR decreased in NAWM (- 0.008 SUVR/year, p = 0.03) and even more so in WMH (- 0.02 SUVR/year, p < 0.001). Between 17% and 66% of the variance of longitudinal changes in cortical WM-referenced [ 18F]flortaucipir SUVRs were explained by longitudinal changes in the reference region. CONCLUSIONS: [ 18F]flortaucipir retention in the WM decreases over time and is influenced by the presence of WMH, supporting the hypothesis that [ 18F]flortaucipir retention in the WM is partially myelin-dependent. These findings have implications for the use of WM reference regions for [ 18F]flortaucipir-PET imaging.
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Authors | Alexis Moscoso, Michel J Grothe, Michael Schöll, Alzheimer’s Disease Neuroimaging Initiative |
Journal | European journal of nuclear medicine and molecular imaging
(Eur J Nucl Med Mol Imaging)
Vol. 48
Issue 7
Pg. 2283-2294
(07 2021)
ISSN: 1619-7089 [Electronic] Germany |
PMID | 33475761
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Carbolines
- 7-(6-fluoropyridin-3-yl)-5H-pyrido(4,3-b)indole
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Topics |
- Aged
- Alzheimer Disease
(diagnostic imaging)
- Carbolines
- Cognitive Dysfunction
(diagnostic imaging)
- Humans
- Positron-Emission Tomography
- White Matter
(diagnostic imaging)
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