New Brain Imaging Method Reveals Insights into Microvessels
Researchers at the Mark and Mary Stevens Neuroimaging and Informatics Institute (Stevens INI) at the Keck School of Medicine of USC have developed an innovative brain imaging technique that tracks how the brain’s tiniest blood vessels pulse with each heartbeat. These subtle fluctuations could provide important clues about aging and conditions like Alzheimer’s disease.
According to a study published in Nature Cardiovascular Research, this research introduces a groundbreaking noninvasive method to assess “microvascular volumetric pulsatility”—essentially the rhythmic expansion and contraction of small blood vessels—in live human subjects. By utilizing ultra-high field 7T magnetic resonance imaging (MRI), the team discovered that these microvessel pulses increase with age, especially in the deep white matter of the brain. This area is crucial for inter-network communication but is also prone to decreased blood flow from distal arteries that deliver blood from the heart. As these pulses strengthen, they might disrupt brain function, contributing to memory loss and the progression of Alzheimer’s disease.
“Arterial pulsation functions like the brain’s natural pump, aiding in fluid movement and waste removal,” explained Danny JJ Wang, PhD, a professor of neurology and radiology at the Keck School of Medicine. He is also the senior author of the study. “For the first time, our method enables observation of how these tiny blood vessel volumes change with age and vascular risks, paving the way for new research on brain health, dementia, and small vessel disease.”
While it has been known that rigidity and excessive pulsation in larger arteries are correlated with stroke, dementia, and small vessel disease, observing these rhythmic changes in the brain’s microvessels has proven nearly impossible without invasive methods typically limited to animal studies.
To address this challenge, the USC researchers combined two advanced MRI techniques: vascular space occupancy (VASO) and arterial spin labeling (ASL). They monitored minute changes in microvessel volume throughout the cardiac cycle. Their findings indicated that older adults show stronger microvascular pulsations in deep white matter compared to their younger counterparts, with hypertension exacerbating this effect. “These discoveries bridge what we observe in large vessel imaging with the microvascular damage seen in aging and Alzheimer’s disease,” noted Fanhua Guo, PhD, the study’s lead author and a postdoctoral researcher in Wang’s lab.
Increased vascular pulsation might also disrupt the brain’s “glymphatic system,” a newly identified network responsible for waste removal, including beta-amyloid—a protein implicated in Alzheimer’s disease. If this fluid circulation is compromised, it could accelerate cognitive decline over time.
“Measuring these tiny vascular pulses in vivo is a significant advancement,” stated Arthur W. Toga, PhD, director of the Stevens INI. “This technology not only enhances our understanding of brain aging but also holds potential for the early diagnosis and monitoring of neurodegenerative disorders.”
The team is investigating how this method might be adapted for broader clinical application, including use on more widely available 3T MRI scanners. Future research will also explore whether microvascular volumetric pulsatility can predict cognitive outcomes and serve as a biomarker for early interventions in Alzheimer’s disease and related conditions.
“This is just the beginning,” Wang remarked. “We aim to transition this from research environments to clinical settings, where it could inform diagnosis, prevention, and treatment strategies for countless individuals at risk of dementia.”
Study Details
Alongside Wang, the study included contributions from Fanhua Guo, Chenyang Zhao, Qinyang Shou, Kay Jann, and Xingfeng Shao of Stevens INI, as well as Ning Jin from Siemens Healthcare.
The research received support from multiple National Institutes of Health (NIH) grants.
