期刊
JOURNAL OF CEREBRAL BLOOD FLOW AND METABOLISM
卷 43, 期 6, 页码 921-936出版社
SAGE PUBLICATIONS INC
DOI: 10.1177/0271678X231152001
关键词
Alzheimer's disease; amyloid-PET; diffusion MRI; free water; white matter
This study investigated the relationship between A beta-PET signal in white matter (WM) regions and diffusion MRI-based microstructural alterations. The results showed that decreased A beta-PET signal in WMH regions was closely associated with higher free water and higher WMH volume, while increased A beta-PET signal in normal-appearing WM was closely associated with higher cortical A beta and lower free water-adjusted FA. Furthermore, cognitive impairment was more closely related to higher free water than to either free water-adjusted FA or WM PET.
White matter (WM) injury is frequently observed along with dementia. Positron emission tomography with amyloid-ligands (A beta-PET) recently gained interest for detecting WM injury. Yet, little is understood about the origin of the altered A beta-PET signal in WM regions. Here, we investigated the relative contributions of diffusion MRI-based microstructural alterations, including free water and tissue-specific properties, to A beta-PET in WM and to cognition. We included a unique cohort of 115 participants covering the spectrum of low-to-severe white matter hyperintensity (WMH) burden and cognitively normal to dementia. We applied a bi-tensor diffusion-MRI model that differentiates between (i) the extracellular WM compartment (represented via free water), and (ii) the fiber-specific compartment (via free water-adjusted fractional anisotropy [FA]). We observed that, in regions of WMH, a decrease in A beta-PET related most closely to higher free water and higher WMH volume. In contrast, in normal-appearing WM, an increase in A beta-PET related more closely to higher cortical A beta (together with lower free water-adjusted FA). In relation to cognitive impairment, we observed a closer relationship with higher free water than with either free water-adjusted FA or WM PET. Our findings support free water and A beta-PET as markers of WM abnormalities in patients with mixed dementia, and contribute to a better understanding of processes giving rise to the WM PET signal.
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