revealed that microvascular pulsations—referred to as microvascular volumetric pulsatility—are amplified in the brain’s deep white matter with advancing age, and these changes are further intensified in individuals with
hypertension. These findings suggest that monitoring such pulsations could improve understanding of cerebral small vessel health and its role in cognitive decline.
The research was led by Fanhua Guo from the Laboratory of FMRI Technology (LOFT), Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California (USC), Los Angeles, along with senior author Danny JJ Wang, PhD. The team combined two advanced imaging techniques—arterial spin labeling (ASL) and four-dimensional vascular space occupancy (4D VASO)—to track subtle volumetric changes in the brain’s microvessels over the cardiac cycle.
The study included 12 older adults with a median age of 60 and 11 younger participants with a median age of 28, allowing the researchers to compare age-related differences in microvascular pulsatility.
Historically, while the relationship between large artery stiffness and risks of stroke, dementia, and small vessel disease has been well documented, assessing pulsations in the brain’s smallest vessels has been challenging. Prior studies were often limited to animal models or invasive procedures, making fine-grained observation in humans difficult. The combination of ASL and 4D VASO in this study overcomes these barriers, enabling high-resolution, in vivo measurement of microvascular pulsatility without invasive methods.
The results showed the following findings:
- Older adults showed significantly higher microvascular pulsatility in deep white matter regions compared to younger individuals.
- Hypertension further amplified microvascular pulsatility in deep white matter.
- The microvascular volumetric pulsatility index (mvPI) in deep white matter correlated with large artery velocity pulsatility, linking micro- and macrovascular function.
- The imaging method demonstrated strong reproducibility and accuracy through test–retest scans and non-parametric reliability testing.
- This non-invasive approach enables detailed examination of how aging affects cerebral microvascular health.
- It allows precise mapping of microvessel pulsatility across cortical layers and white matter.
- The technique may help detect early vascular changes contributing to neurodegenerative disorders, including Alzheimer’s disease.
- The method has potential implications for understanding glymphatic function, neurodegeneration, and cognitive decline.
The study highlights the value of high-resolution, 7-tesla MRI combined with advanced ASL and 4D VASO techniques in advancing our understanding of cerebral microvascular physiology.
"As research in this area continues, such imaging tools may help guide interventions to preserve vascular health and cognitive function in aging populations, potentially transforming how clinicians monitor and manage neurovascular risk in older adults," the authors concluded.
Reference:
Guo, F., Zhao, C., Shou, Q., Jin, N., Jann, K., Shao, X., & Wang, D. J. (2025). Assessing cerebral microvascular volumetric with high-resolution 4D cerebral blood volume MRI at 7 T. Nature Cardiovascular Research, 1-15. https://doi.org/10.1038/s44161-025-00722-1
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