Dear Michael,
To be clear, was every subject scanned at every site? So, for example, were all subjects scanned at site A for session 1, site B for session 2 etc? Or were some subjects scanned at different sites?
If every subject was scanned at every site, then including a regressor for site in your first level GLM (prior to extracting ROIs for DCM) should be fine. If different subjects were scanned at different sites, i.e. site is a between-subjects factor, then something more involved might be needed.
Best,
Peter.
Peter Zeidman, PhD
Methods Group
Wellcome Trust Centre for Neuroimaging
12 Queen Square
London WC1N 3BG
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-----Original Message-----
From: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]] On Behalf Of Mouthon Michaƫl
Sent: 29 September 2014 14:19
To: [log in to unmask]
Subject: [SPM] DCM analysis for a multisite fMRI study
Dear SPM and DCM users,
I have conducted a fMRI experiment on several sites (with different MRI scanners).
I would like to conduct a DCM analysis (with the same model) on each participant.
Can I compare directly the strength of intrinsic connections compute by DCM between my subjects acquired in different scan places (as the DCM estimation is within-subject analysis)? Or do I need to take account about the acquisition site when I compare them (e.g. add a regressor)?
Thank you very much in advance
Michael
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