Characterizing cerebral hemodynamics across the adult lifespan with arterial spin labeling MRI data from the Human Connectome Project-Aging

Abstract

Arterial spin labeling (ASL) magnetic resonance imaging (MRI) has become a popular approach for studying cerebral hemodynamics in a range of disorders and has recently been included as part of the Human Connectome Project-Aging (HCP-A). Due to the high spatial resolution and multiple post-labeling delays, ASL data from HCP-A holds promise for localization of hemodynamic signals not only in gray matter but also in white matter. However, gleaning information about white matter hemodynamics with ASL is challenging due in part to longer blood arrival times in white matter compared to gray matter. In this work, we present an analytical approach for deriving measures of cerebral blood flow (CBF) and arterial transit times (ATT) from the ASL data from HCP-A and report on gray and white matter hemodynamics in a large cohort ( n = 234) of typically aging adults (age 36–90 years). Pseudo-continuous ASL data were acquired with labeling duration = 1500 ms and five post-labeling delays = 200 ms, 700 ms, 1200, 1700 ms, and 2200 ms. ATT values were first calculated on a voxel-wise basis through normalized cross-correlation analysis of the acquired signal time course in that voxel and an expected time course based on an acquisition-specific Bloch simulation. CBF values were calculated using a two-compartment model and with age-appropriate blood water longitudinal relaxation times. Using this approach, we found that white matter CBF reduces ( ρ = 0.39) and white matter ATT elongates ( ρ = 0.42) with increasing age ( p < 0.001). In addition, CBF is lower and ATTs are longer in white matter compared to gray matter across the adult lifespan (Wilcoxon signed-rank tests; p < 0.001). We also found sex differences with females exhibiting shorter white matter ATTs than males, independently of age (Wilcoxon rank-sum test; p < 0.001). Finally, we have shown that CBF and ATT values are spatially heterogeneous, with significant differences in cortical versus subcortical gray matter and juxtacortical versus periventricular white matter. These results serve as a characterization of normative physiology across the human lifespan against which hemodynamic impairment due to cerebrovascular or neurodegenerative diseases could be compared in future studies.

The European Prevention of Alzheimer’s Dementia (EPAD) MRI Dataset and Processing Workflow

“…Previous publications agree with our result of reduced TBSS values in amyloid-positive individuals (Collij et al 2020). Finally, A decline of CBF in the GM has been widely reported in recent studies of elderly individuals (Juttukonda et al 2021). Previous studies on CBF with APOE genotype have shown higher brain perfusion related to worse cognitive impairment in older adults carrying the APOE e4 allele (Zlatar et al 2016), and higher regional perfusion in e4 carriers in the left cingulate and lateral frontal and parietal regions (McKiernan et al 2020).…”

A Prospective, Longitudinal Magnetic Resonance Imaging Evaluation of Cerebrovascular Reactivity and Infarct Development in Patients With Intracranial Stenosis

“…Mean hemodynamic measures were compared within participants inside this mask in the stenosed hemisphere and in the analogous region in the non‐stenosed hemisphere using a Wilcoxon signed‐rank test in each participant group separately. This approach was used to control for partial volume effects, as hemodynamic reactivity and perfusion differ between gray and white matter 24,25 . Next, to assess whether hemodynamic impairment due to stenosis is similar in atherosclerotic and non‐atherosclerotic disease, laterality indices (Eq. )…”

“…This approach was used to control for partial volume effects, as hemodynamic reactivity and perfusion differ between gray and white matter. 24,25 Next, to assess whether hemodynamic impairment due to stenosis is similar in atherosclerotic and nonatherosclerotic disease, laterality indices (Eq. 1) were computed for CBF and all CVR measures between regions in stenosed and nonstenosed (i.e., contralateral) hemispheres in each participant group and compared using a Wilcoxon rank-sum test:…”

Reliability and Reproducibility of Hadamard Encoded Pseudo-Continuous Arterial Spin Labeling in Healthy Elderly

“…In our study we could confirm the results shown in Cohen et al (2020), that ATT was more reliable than CBF. This further approves, that the ATT should be accounted for in perfusion studies, especially in those investigating aging (Juttukonda et al, 2021) and elderly (Dai et al, 2017) or patients suffering from neurodegenerative diseases (Suo et al, 2019). There are two reasons to estimate ATT: It is a valuable hemodynamic parameter as noted above, and a correct ATT is sensible for the CBF quantification.…”