Abstract #4865

Assessing cerebral perfusion: analysis of the BOLD response to a hypoxia-induced step change in deoxyhemoglobin

James Duffin^1,2, Ece Su Sayin¹, Olivia Sobczyk^3,4, Julien Su Poublanc⁵, David Mikulis⁵, and Joseph A. Fisher^3,6

¹Physiology, University of Toronto, Toronto, ON, Canada, ²Anaesthesiology and Pain Management, University of Toronto, Toronto, ON, Canada, ³Department of Anaesthesiology and Pain Management, University of Toronto, Toronto, ON, Canada, ⁴Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada, ⁵Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada, ⁶Toronto General Hospital Research Institute, University Health Network, Toronto, ON, Canada

Synopsis

Keywords: Contrast Agents, Perfusion, brain

Motivation: Provide direct measurements of cerebral perfusion metrics, relative cerebral blood flow and volume, and mean transit time.

Goal(s): Generate a known step susceptibility contrast input rather than requiring back calculation of an arterial input function

Approach: We used a step reoxygenation of previously deoxygenated lung alveoli to induce a step increase in oxyhemoglobin in arterial blood and analyzed the T2*-weighted signal for each voxel. Perfusion metrics from step deoxyhemoglobin changes were compared to those from conventional analysis using a gadolinium contrast agent in healthy volunteers.

Results: The perfusion metrics from the step deoxyhemoglobin method were similar to those from Gadolinium injection.

Impact: Perfusion metrics can be measured directly from a non-invasive test using a step decrease in deoxyhemoglobin generated by instantaneous reoxygenation from a brief hypoxia. They correspond to those calculated indirectly from an intravenously injected Gadolinium contrast agent involving complex analysis.

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