Intra-vital visualization of deep cerebrovascular structures and blood flow in the
aging brain has been a difficult challenge in the field of neurovascular research,
especially when considering the key role played by the cerebrovasculature in the pathogenesis
of both vascular cognitive impairment and dementia (VCID) and Alzheimer’s disease
(AD). Traditional imaging methods face difficulties with the thicker skull of older
brains, making high-resolution imaging and cerebral blood flow (CBF) assessment challenging.
However, functional ultrasound (fUS) imaging, an emerging non-invasive technique,
provides real-time CBF insights with notable spatial-temporal resolution. This study
introduces an enhanced longitudinal fUS method for aging brains. Using elderly (24-month
C57BL/6) mice, we detail replacing the skull with a polymethylpentene window for consistent
fUS imaging over extended periods. Ultrasound localization mapping (ULM), involving
the injection of a microbubble (<<10 μm) suspension allows for recording of high-resolution
microvascular vessels and flows. ULM relies on the localization and tracking of single
circulating microbubbles in the blood flow. A FIJI-based analysis interprets these
high-quality ULM visuals. Testing on older mouse brains, our method successfully unveils
intricate vascular specifics even in-depth, showcasing its utility for longitudinal
studies that require ongoing evaluations of CBF and vascular aspects in aging-focused
research.
