Assessing cerebral microvascular volumetric with high-resolution 4D cerebral blood volume MRI at 7 T, 2025, Guo et al.

SNT Gatchaman

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Assessing Cerebral Microvascular Volumetric Pulsatility with High-Resolution 4D CBV MRI at 7T
Fanhua Guo; Chenyang Zhao; Qinyang Shou; Ning Jin; Kay Jann; Xingfeng Shao; Danny JJ Wang

Arterial pulsation is crucial for promoting fluid circulation and for influencing neuronal activity. Previous studies assessed the pulsatility index based on blood flow velocity pulsatility in relatively large cerebral arteries of human. Here, we introduce a novel method to quantify the volumetric pulsatility of cerebral microvasculature across cortical layers and in white matter (WM), using high-resolution 4D vascular space occupancy (VASO) MRI with simultaneous recording of pulse signals at 7T.

Microvascular volumetric pulsatility index (mvPI) and cerebral blood volume (CBV) changes across cardiac cycles are assessed through retrospective sorting of VASO signals into cardiac phases and estimating mean CBV in resting state (CBV0) by arterial spin labeling (ASL) MRI at 7T. Using data from 11 young (28.4+-5.8 years) and 7 older (61.3+-6.2 years) healthy participants, we investigated the aging effect on mvPI and compared microvascular pulsatility with large arterial pulsatility assessed by 4D-flow MRI.

We observed the highest mvPI in the cerebrospinal fluid (CSF) on the cortical surface (0.19+-0.06), which decreased towards the cortical layers as well as in larger arteries. In the deep WM, a significantly increased mvPI (p = 0.029) was observed in the older participants compared to younger ones. Additionally, mvPI in deep WM is significantly associated with the velocity pulsatility index (vePI) of large arteries (r = 0.5997, p = 0.0181). We further performed test-retest scans, non-parametric reliability test and simulations to demonstrate the reproducibility and accuracy of our method.

To the best of our knowledge, our method offers the first in vivo measurement of microvascular volumetric pulsatility in human brain which has implications for cerebral microvascular health and its relationship research with glymphatic system, aging and neurodegenerative diseases.


Link | PDF (Preprint: MedRxiv) [Open Access]
 
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Published in Sep 2025 as —

Assessing cerebral microvascular volumetric with high-resolution 4D cerebral blood volume MRI at 7 T
Guo, Fanhua; Zhao, Chenyang; Shou, Qinyang; Jin, Ning; Jann, Kay; Shao, Xingfeng; Wang, Danny Jj

Arterial pulsation is crucial for promoting neurofluid circulation. Most previous studies quantified pulsatility via blood velocity-based indices in large arteries. Here we propose an innovative method to quantify the microvascular volumetric pulsatility index (mvPI) across cortical layers and white matter (WM) using high-resolution four-dimensional (4D) vascular space occupancy (VASO) and arterial spin labeling (ASL) magnetic resonance imaging (MRI) at 7 T with simultaneous pulse recording.

We assessed aging-related changes in mvPI in 11 young (28.4 ± 5.8 years) and 12 older (60.2 ± 6.8 years) participants and compared mvPI with large artery pulsatility assessed by 4D-flow MRI. mvPI peaked in the pial surface (0.18 ± 0.04).

Deep WM mvPI was significantly higher in older participants (P = 0.006) than young ones. Deep WM mvPI correlated with large artery velocity PI (r = 0.56, P = 0.0099). We performed test–retest scans, non-parametric reliability test and simulations to demonstrate the reproducibility and accuracy of the method.

In conclusion, our non-invasive method enables in vivo fine-grained measurement of mvPI, with implications for glymphatic function, aging and neurodegenerative diseases.

Web | DOI | PDF | Nature Cardiovascular Research | Open Access
 
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