Abstract #3475

Modeling the Effect of Changes in Hematocrit, O2 Extraction Fraction, and Blood Volume Distribution on the BOLD Signal and Estimates of CMRO2 Change with a Calibrated BOLD Method

Valerie Griffeth^1,2, Richard Buxton³

¹Department of Bioengineering, University of California, San Diego, La Jolla, CA, United States; ²Medical Scientist Training Program, University of California, San Diego, La Jolla, CA, United States; ³Department of Radiology, University of California, San Diego, La Jolla, CA, United States

We applied a calibrated-BOLD methodology to assess effects of caffeine consumption on coupling of CBF and cerebral metabolic rate of O2 (CMRO2) responses to a visual stimulus. Although the BOLD responses were similar, we found an increase in *** CMRO2 change after administration of caffeine, both as a fraction of the current baseline state and in a more absolute sense referred to the pre-caffeine baseline. More modest changes were found in the CBF response, leading to a decrease of the CBF/CMRO2 coupling ratio.