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J Cereb Blood Flow Metab. 2018 Mar;38(3):528-539. doi: 10.1177/0271678X17701948. Epub 2017 Mar 31.

Stimulus-evoked changes in cerebral vessel diameter: A study in healthy humans.

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1 Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, QC, Canada.
2 Molecular Imagery Center of Sherbrooke (CIMS), Clinical Research Center (CRC) of Sherbrooke University Hospital Center (CHUS), Sherbrooke, QC, Canada.
3 MR Clinical Science, Philips Healthcare, Markham, ON, Canada.
4 Department of Diagnostic Radiology, Université de Sherbrooke, Sherbrooke, QC, Canada.
5 Division of Neurology, Department of Medicine, and Research Center on Aging, Université de Sherbrooke, Sherbrooke, QC, Canada.
6 Department of Computer Science, Université de Sherbrooke, Sherbrooke, QC, Canada.


The high metabolic demand of neuronal tissue, coupled with its relatively low energy storage capacity, requires that increases in neuronal activation are quickly matched with increased blood flow to ensure efficient supply of oxygen and nutrients to the tissue. For this to occur, dilation of nearby arterioles must be coordinated with the dilation of larger upstream feeding arteries. As it stands, the exact spatial extent of such dilation in humans is unknown. Using non-invasive time-of-flight magnetic resonance angiography in healthy participants, we developed an automatic methodology for reconstructing cerebral arterial vessels and quantifying their diameter on a voxel-by-voxel basis. Specifically, we isolated the posterior cerebral artery (PCA) supplying each occipital lobe and quantified its vasodilation induced by visual stimulation. Stimulus-induced changes were strongest (∼30%) near primary visual cortex and progressively decreased in a non-linear fashion as a function of distance. Surprisingly, weak - albeit significant - changes (∼2%) were observed ∼70 mm from the visual cortex. This demonstrates that visual stimulation modulates vascular tone along the bulk of the PCA segment, and thus may have important implications for our understanding of functional hyperemia in healthy and diseased states.


Arterial vessels; automated segmentation; diameter; long-distance vasodilation; time-of-flight magnetic resonance angiography

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