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Abstract #3340

Comparison of ASL Measures of Cerebrovascular Reactivity to CO2 Using Different Respiratory Manipulations

Felipe B. Tancredi1, 2, Richard D. Hoge1, 2

1Institut de gnie biomdical, Universit de Montral, Montreal, Quebec, Canada; 2Unit de neuroimagerie fonctionnelle, CRIUGM, Montreal, Quebec, Canada

ASL measurements of the cerebrovascular reactivity to CO2 (CVR) provide an index of the cerebral vasculatures health status and are also an important input for calibrated MRI. CVR is expressed as the increase in ASL-flow signal that is induced per unit increase in respiratory levels of CO2. We examined whether different respiratory manipulations lead to consistent measures of CVR. We found that because of the non-linearity of CO2-CBF dose-response curve, CVR values differ according to the manipulated levels of CO2. However, estimates tend to converge when CVR is expressed as the percent increase in flow signal.