High-frequency ultrasound imaging of the cerebral blood vessels in rodent models

Ultrasound-based cerebral vascular imaging in rodent models has the potential to provide insight into time-resolved relationships between vessel-level hemodynamics and various brain activities. Achieving both high spatial resolution and sufficient imaging speed remains a challenge, particularly due to signal attenuation and weak scattering from small vessels when using high-frequency ultrasound. To address these limitations, we developed a cerebral vascular imaging framework combining high-frequency ultrasound with microbubble contrast enhancement, aiming to achieve whole-brain, high-contrast vascular imaging in mice. A 30-MHz linear transducer was mechanically translated 5 mm in the elevational direction at 1 mm/s to acquire volumetric flow data. Data were collected from an 8-week-old C57BL/6 mouse before and after tail vein injection of microbubbles. A custom signal processing pipeline involving section-wise SVD filtering and power Doppler imaging was applied. Prior to contrast injection, vascular structures were visualized up to 3 mm below the cortical surface. After microbubble injection, deeper structures including the circle of Willis at 6 mm in depth, along with fine vascular networks branching from the major arteries, became visible. These findings demonstrate the feasibility of contrast-enhanced high-frequency ultrasound for whole brain vascular imaging and its potential for neurovascular studies in small animals.