Two-Dimensional Super-Resolution Visualization of Rat Brain Microvasculature Using Ultrasound Localization Microscopy.

The cerebral microvasculature forms a complex network of vessels essential for maintaining brain function. Diseases such as stroke, Alzheimer's disease, gliomas, and vascular dementia can profoundly disrupt the microvascular system. Unfortunately, current medical imaging modalities offer only indirect observations at this scale. Inspired by optical microscopy, ultrasound localization microscopy (ULM) overcomes the classical trade-off between penetration depth and spatial resolution. By localizing and tracking individual injected microbubbles (MBs) with sub-wavelength precision, vascular and velocity maps can be generated at the micrometer scale. Here, we present a robust protocol for super-resolution imaging of the brain microvasculature in vivo in rats using a commercial ultrasound platform. This method achieves 12.5 µm spatial resolution, reconstructing the microvascular architecture and providing detailed information on blood flow direction and velocity, greatly enhancing our understanding of cerebral microcirculation. The protocol can be extended to rat disease models, offering a powerful tool for the early diagnosis and treatment of neurovascular diseases.