acquisition in 1 session vs 2 sessions - Freesurfer

13 Nov 2013


      Thanks a lot Doug, We have followed your suggestion and now fMRI is
the third sequence. Both patients and controls will have two sessions
too.
Best
Daniel
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Message: 1
Date: Sat, 09 Nov 2013 12:50:39 -0500
From: Douglas Greve greve@nmr.mgh.harvard.edu
Subject: Re: [Freesurfer] acquisition in 1 session vs 2 sessions
To: freesurfer@nmr.mgh.harvard.edu
Message-ID: 527E75EF.2070807@nmr.mgh.harvard.edu
Content-Type: text/plain; charset="iso-8859-1"
I think the only thing you would have to worry about is the fMRI since
the way the subject reacts to the task (or state of subject during rest)
might change depending upon how long he/she has been in the scanner. Why
not do the fMRI at #3? Then each population would be in the scanner for
the same amount of time. If the T1 and FLAIR are bandwidth matched, I'd
do them in the same session. The only other confound could be that your
controls might move more in the last couple of scans since they will
have been in the scanner for a while at that point. Depending on your
patient population, there might be difference in movement anyway. There
should not be any problems with analyzing the data regardless of how you
slice it up.
doug
On 11/9/13 3:56 AM, Daniel Ferreira wrote:
Dear experts,
We are designing a study including a long MR protocol:
1) Localizer
2) Cal
3) T1-FSPGR
4) FLAIR 3D
5) DTI 1
6) DTI 2
7) fMRI
Due to patients characteristics we were thinking on splitting the
acquisition in two different sessions (session 1: sequences 1, 2, 3,
4; session 2: sequences 1, 2, 5, 6, 7).
Do you think we should do the same for the healthy controls or we can
scan them in just one single session? I wonder how system
session-related artifacts could differentially affect the two kinds of
protocol (spitted vs. single). I also wonder how FreeSurfer processing
can be affected by this issues.
Thanks a lot.
Daniel Ferreira
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