Dear SPMers,
I am analyzing fMRI images. My study design has two groups (experimental and control) and two MRI acquisitions per subject (pre and post treatment). I would like to explore possible changes in brain activation after an intervention. Consequently, I want use the subtraction method to obtain each subject´s brain activation changes using IMcalc (i1-i2) and then introduce the obtained images in a two sample t-test analysis.
However, I am not sure about how the IMcalc tool works. Consequently, I do not know if I should check post minus pre and pre minus post brain changes, or if I would obtain the same results in both cases. The SPM manual does not explain IMcalc functioning and I do not find an answer for this basic question in the SPM forum, so I would be very grateful for an answer to this question.
Thank you in advance,
Oiane
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