Ian Driver1, Kay Head1, Penny Gowland1, Susan Francis1
1Sir Peter Mansfield Magnetic Resonance
There has been much interest in how spatial extent of activation and the shape of the haemodynamic response alters with field strength, due to differing extravascular and intravascular signal contributions. We apply an event-related visual stimulus with long inter-stimulus-interval to assess the temporal features of the BOLD response. Findings show high similarity between hrf shapes across field strength, despite a decrease in relative IV/EV fraction of BOLD contrast with increased field. Time-to-peak maps show tissue areas are highly homogenous, with large deviances occurring only in the large vessels.