We are analyzing repeated scans, two for each participant, and we have reason to believe that physiological functioning may have changed between the scans. In short, differences in activity during the task between the two scans are reduced to not meeting the statistical significance threshold when we use RVT and RETROICOR (but are present when we do not include them). We would like to have some way of determining what changes in physiological functioning may be responsible, and are calculating respiration rate and heart rate during each scan, but we would also like to look at potential differences in RVT. We were wondering if the values found in the “RVT.1D” file for each subject could be utilized for each purpose, for example by averaging the values for scan 1 and scan 2 and comparing them. Any thoughts or help on this would be much appreciated.