Hello,
I am doing a perfusion analysis and am deciding between using the "perfusion subtraction" option under pre-stats processing or doing the "full signal modeling". I need to run pre-stats separately from the full analysis, so my options are to 1) run prestats with the subtraction option on and then do the higher level analysis modeling the BOLD only or 2) run prestats with subtraction off then do the higher level analysis with the full perfusion signal modeling.
I did it both ways and it looks totally different. Why should the results be different and which method is better?
I am following the directions from here:
http://www.fmrib.ox.ac.uk/fsl/feat5/perfusion.html
Thank you,
Natalie
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