Ian David Driver1, Nicholas P. Blockley2, Susan T. Francis1, Penny A. Gowland1
1SPMMRC, School of Physics and Astronomy,
University of Nottingham, Nottingham, UK; 2SPMMRC, School of Physics
and Astronomy, University of Nottingham, Nottingham, UK
The BOLD signal response to mild hypercapnia provides useful information about the BOLD haemodynamic response and has applications in cerebrovascular diseases. Typical problems in previous experiments include poor information regarding end-tidal gas concentrations and a coupling between CO2 and O2 levels. This study used high resolution imaging to reduce partial volume effects and a system providing independent control of end tidal CO2 and O2. Rapid monitoring of end-tidal CO2 enabled correlation of the BOLD signal against actual hypercapnic level at each time point rather than prescribed level of hypercapnia. This provided sufficient sensitivity to observe both grey and white matter reactivity in response to hypercapnia.