Mapping vascular network architecture in primate brain using ferumoxytol-weighted laminar MRI

Area of Science:

• Neuroimaging
• Vascular Biology
• Primate Neuroscience

Background:

• Mapping brain vasculature is crucial for understanding neuroimaging, radiology, and neurology.
• Current methods face challenges in precisely mapping vasculature across brain regions and cortical layers.
• Limited understanding exists regarding neurometabolic factors influencing the brain's microvasculature.

Purpose of the Study:

• To investigate whole-brain vascular volume using advanced MRI techniques in macaque monkeys.
• To validate findings with existing data on vascular densities and compare them with cytoarchitecture, neuron, and synaptic densities.
• To establish a link between neurometabolic factors and vascular network architecture in the primate brain.

Main Methods:

• Ferumoxytol-weighted laminar-resolution multi-echo gradient-echo imaging was employed in macaque monkeys.
• The change in transverse relaxation rate (ΔR2*) as a proxy for cerebral blood volume (CBV) was mapped onto cortical surfaces.
• Image resolution was adjusted based on critical sampling frequency to delineate arterial-venous vessels.

Main Results:

• CBV exhibited a 3-fold variation across the brain, with the highest volume in the inferior colliculus and lowest in the corpus callosum.
• Cortical CBV was high in primary sensory areas and low in association areas, correlating with neuron and receptor densities.
• Translaminar vascular network motifs were identified, suggesting distinct energy supply requirements across brain regions.

Conclusions:

• The study provides significant methodological and conceptual advancements in cerebrovascular MRI.
• Findings link neurometabolic factors to vascular network architecture in the primate brain.
• The research refines our understanding of brain vascular organization and its relation to function.