A novel MRI technique enables the first layer-resolved mapping of cerebral microvascular volumetric pulsatility across cortical and white matter regions. Credit: Stevens INI
A newly developed brain imaging technique which uses ultra-high field MRIs can detect tiny blood vessels in the brain that pulse with each heartbeat.
The researchers behind the novel method suggest that it will be used to detect the early stages of Alzheimer’s disease and track changes in ageing brains.
Alzheimer’s disease is the most common form of dementia. It is currently the seventh leading cause of death and one of the major causes of disability in older people worldwide.
This imaging technique provides the first non-invasive method for measuring microvascular volumetric pulsatility, which are contractions of tiny brain vessels.
Using the new imaging device, the team showed that the brain’s blood vessels increasingly pulse with age, especially in the deep white matter regions. White matter in the brain is responsible for communication between brain networks. It is believed that an increase in micro vessel pulses may disrupt this white matter communication and potentially speed up memory loss and Alzheimer’s disease.
Recent studies have also found that fast brain pulses may also impair the function of the brain’s glymphatic system, the part of the brain that cleans away beta-amyloid proteins that cause Alzheimer’s.
The researchers hope their findings will guide future studies towards new Alzheimer’s prevention and treatment strategies.
“Arterial pulsation is like the brain’s natural pump, helping to move fluids and clear waste,” says senior author of the study Danny Wang, from the University of Southern California’s Keck School of Medicine in the US.
“Our new method allows us to see, for the first time in people, how the volumes of those tiny blood vessels change with aging and vascular risk factors. This opens new avenues for studying brain health, dementia, and small vessel disease.”
While previous research has uncovered a link between pulsatility and dementia, small vessel disease and stroke, measuring these pulsations involved invasive methods.
Less invasive ones have only been used in animal studies.
“Being able to measure these tiny vascular pulses in vivo is a critical step forward,” says Arthur Toga, director of USC’s Mark and Mary Stevens Neuroimaging and Informatics Institute.
“This technology not only advances our understanding of brain aging but also holds promise for early diagnosis and monitoring of neurodegenerative disorders.”
The team developed their imaging method by combining 2 advanced MRI techniques: vascular space occupancy (VASO), an MRI approach that measures changes in blood volume, and arterial spin labelling (ASL) which tracks water flow in the brain.
Using these 2 approaches together means the researchers can track small volume changes in microvessels that may have otherwise gone unnoticed.
“These findings provide a missing link between what we see in large vessel imaging and the microvascular damage we observe in aging and Alzheimer’s disease,” says Fanhua Guo, lead author of the study.
The research team intend to continue developing their imaging technique so that it can be used in a wider clinical setting on commonly available MRI machines. Although further research is needed, they are hopeful microvascular volumetric pulsatility may one day serve as a non-invasive biomarker for early intervention in Alzheimer’s disease.
“This is just the beginning,” says Wang.
“Our goal is to bring this from research labs into clinical practice, where it could guide diagnosis, prevention, and treatment strategies for millions at risk of dementia.”
The results from this study have been published in Nature Cardiovascular Research.