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Abstract #2997

Mild Hypercapnia Causes a Measurable Change in Cerebral Oxygen Extraction Fraction (OEF)

Rajiv G. Menon1, Charles G. Cantrell1, Edward G. Walsh2, Donald B. Twieg3, Timothy J. Carroll1

1Radiology Department, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States; 2Neuroscience, Brown University, Providence, RI, United States; 3Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL, United States

OEF(Oxygen Extraction Fraction) is shown to be an independent predictor of stroke We previously reported an MR technique to measure OEF. Here we show that we can measure dynamic changes in OEF (OEF Reactivity) by inducing mild hypercapnia using a breath-hold experiment. We tested the method on 5 normal volunteers and demonstrate that we can measure OEF changes related to mild physiologic stress. OEF reactivity as a surrogate measure of cerebrovascular reserve would provide supplemental information in patients who receive diamox/acetazolamide challenge to determine information on collateralization, and correlate with more favorable outcomes in revascularization therapy.