In vivo 7 Tesla MRI of non-human primate intracortical microvascular architecture.

Intracortical arterioles are key locations for blood flow regulation and oxygen supply in the brain and are critical to brain health and disease. However, imaging such small (<100-μm-sized) vessels in humans is challenging. Here, using non-human primates as a model, we developed a capability for imaging microvasculature in vivo with a clinical 7 T MRI scanner. Using simulations, we identified parameters for imaging intracortical vessels with slow flow and combined this with high-resolution imaging (64 × 64 μm² in-plane). Across large swaths of occipital, parietal, and temporal cortex, arrays of intracortical arterioles and venules were observed in gyral crowns and deep within sulcal folds. Systematic arteriole-venule patterns revealed potential architecture of input-output flow relationships. Even single vessels could be followed across cortical laminae. As a first step toward imaging microvasculature in humans, this method introduces a new technology and animal model for understanding relationships between functional and vascular architectures.