Abstract #0215

Progression of visual-stimulus-evoked blood velocity response timing across individual arteries and veins measured with phase-contrast fMRA

Zhangxuan Hu^1,2, Sébastien Proulx^1,2, Divya Varadarajan^1,2, Daniel E. P. Gomez^1,2,3, Saskia Bollmann⁴, and Jonathan R. Polimeni^1,2,5

¹Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, ²Department of Radiology, Harvard Medical School, Boston, MA, United States, ³Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, United States, ⁴School of Information Technology and Electrical Engineering, Faculty of Engineering, Architecture and Information Technology, The University of Queensland, Brisbane, Australia, ⁵Harvard-MIT Program in Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States

Synopsis

Keywords: fMRI Acquisition, fMRI Acquisition

Motivation: Macrovasculature plays an important role in neurovascular coupling, yet most of what is known has focused on the communication between neurons and microvasculature.

Goal(s): To measure real-time blood-velocity responses across several stages of the cerebral macrovasculature to better understand the hemodynamic response across the vascular hierarchy.

Approach: A phase-contrast functional MRA (PC-fMRA) approach was used to measure visual-stimulation-induced velocity responses concurrently within multiple vessels: along major arteries, pial arteries, pial veins, major veins and sinuses.

Results: Robust velocity increases were measured within individual vessels. Observed latencies in the venous responses compared with arterial responses reveal a progression of hemodynamic responses across the vasculature.

Impact: We measured neuronal activity-induced blood velocity responses across several stages of the macrovasculature. The mismatches in arterial and venous hemodynamic response timing can provide insight into tissue/microvascular hemodynamics, such as microvascular blood volume changes with activation.

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