you could still use melodic by creating a fake meldoic_mix and regress these out.
cheers-
andreas
________________________________
Von: FSL - FMRIB's Software Library im Auftrag von Doug Greve
Gesendet: Do 05.07.2007 18:40
An: [log in to unmask]
Betreff: Re: [FSL] persistant motion even after mcflirt.
oops, sorry, I did not see that you were using melodic (I had assumed
feat), so ignore what I just wrote!
doug
On Thu, 5 Jul 2007, Peter Fried wrote:
> Hi,
>
> I have a question about correcting for motion in resting-state fmri data.
>
> We collect 180 volumes (TR=2s) of fmri data during a resting-state. The
> data is first processed using the pre-stats tab under FEAT. The parameters
> we use are:
>
> Motion Correction (mcflirt)
> B0 unwarping
> Slice-timing correction
> Bet brain extraction
> Spatial smoothing FWHM = 6 mm
> Intensity Normalisation
> Highpass temporal filtering
>
> plus, Melodic
>
> Here's the problem: MCFLIRT seems to do a good job when there is gradual
> movement over the course of the scan. However, if there is a sudden
> movement (say, the subject coughed or jerked their arm), MCLFIRT does not
> seem to be able to correct it. To make matters worse, there are often
> motion spikes that show up in the timecourse of non-motion components.
>
> We've tried filtering out some of the worst melodic components, but that
> doesn't seem to effect components that have been (for lack of a better
> term) corrupted by motion. The best results we've had have been from
> splitting the 4D volume, removing the volumes with the most motion and
> merging the remaining volumes back together. Even though we don't have a
> block design, I'm still wary of doing this, especially if there is a
> better way.
>
> Here's my question: Is there any way to do a more robust elimination of
> motion, other than the parameters I've mentioned above? Also, should
> deleting volumes be avoided at all costs or is it okay to remove a few
> with bad motion?
>
> Thanks.
> -Pete
>
>
>
--
Douglas N. Greve, Ph.D.
MGH-NMR Center
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