I would think you could not compare them directly, unless you have an equal # of timepoint1 and timepoint2 datasets with the different parameters.
That is, if you have say 12 subjects, and 6 at timepoint 1 had thickness 5 and 6 have thickness 7, and the same for timepoint 2.
Otherwise, the differences you obtain in your analysis cannot be separated from differences due to acquisition parameters.
From: SPM (Statistical Parametric Mapping) [[log in to unmask]] on behalf of Zoe Dadi [[log in to unmask]]
Sent: Friday, November 04, 2011 10:38 AM
To: [log in to unmask]
Subject: [SPM] Different fMRI acquisition parameters in different timepoints_comparable?
Dear SPM users,
I have some fMRI data from subjects from two different time-points with the same task. I want to compare to see if there is any difference between past and current time point.
The acquisition parameters are slightly different though.
Past and present time point have the following common parameters: TE =40; TR=2000, flip angle=70, matrix size= 64x64
But differ in No of slices, past=16, current=25/4
and slice thickness/gap, past=7/0.7 and current 5/0.5
Can I compare them directly? Or is that a problem? And if yes is there anything I can do to overcome it?
Thanks so much in advance.