Hi, Would you please advise if it is possible to do longitudinal statistical analysis within a group with two time points in Qdec. And if it is not possible in Qdec how I suppose to do it?
Best regards, Amirhossein Manzouri
you can't do it in qdec, use the "command line stream", ie, mris_preproc, mri_surf2surf to smoooth, mri_glmfit, and mri_glmfit-sim
doug On 01/30/2014 09:18 AM, amirhossein manzouri wrote:
Hi, Would you please advise if it is possible to do longitudinal statistical analysis within a group with two time points in Qdec. And if it is not possible in Qdec how I suppose to do it? Best regards, Amirhossein Manzouri
Hi,
with one group you want to check if atrophy is significantly different from zero? That is probably the case for any group (e.g. aging), so it won't tell you anything really. Also, if you don't find atrophy in a region it doesn't mean it's not there (only your group size is too small to detect it). So the only real use I can think of, would be a test-retest study, where the assumption is that there is no change?
Sadly Qdec cannot do 'one sample group mean', otherwise you could do that in qdec. If only you had a second 'control' group, then it could be done. You can use long_mris_slopes to compute rate or percent change maps (one for each subjects) and then you can use qdec to analyze those rate maps across groups. If you don't have a control group, you could still use long_mris_slopes (it can also map and stack the rate maps on fsaverage) and then simply run the one sample group mean in mri_glmfit.
some info is also here: https://surfer.nmr.mgh.harvard.edu/fswiki/FsTutorial/LongitudinalTutorial_fr... and https://surfer.nmr.mgh.harvard.edu/fswiki/LongitudinalTwoStageModel
Best, Martin
On 01/30/2014 09:18 AM, amirhossein manzouri wrote:
Hi, Would you please advise if it is possible to do longitudinal statistical analysis within a group with two time points in Qdec. And if it is not possible in Qdec how I suppose to do it? Best regards, Amirhossein Manzouri
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
Dear Doug and Martin, Thanks a lot. I just have one group including 20 subjects. The scans have been done in a range of 0.9 to 1.5 years difference (tp2-tp1). Is ooh if I use the instructions from Paired Analysis : https://surfer.nmr.mgh.harvard.edu/fswiki/PairedAnalysis ? Regards,
Best regards, Amirhossein Manzouri
On Thu, Jan 30, 2014 at 10:31 PM, Martin Reuter <mreuter@nmr.mgh.harvard.edu
wrote:
Hi,
with one group you want to check if atrophy is significantly different from zero? That is probably the case for any group (e.g. aging), so it won't tell you anything really. Also, if you don't find atrophy in a region it doesn't mean it's not there (only your group size is too small to detect it). So the only real use I can think of, would be a test-retest study, where the assumption is that there is no change?
Sadly Qdec cannot do 'one sample group mean', otherwise you could do that in qdec. If only you had a second 'control' group, then it could be done. You can use long_mris_slopes to compute rate or percent change maps (one for each subjects) and then you can use qdec to analyze those rate maps across groups. If you don't have a control group, you could still use long_mris_slopes (it can also map and stack the rate maps on fsaverage) and then simply run the one sample group mean in mri_glmfit.
some info is also here:
https://surfer.nmr.mgh.harvard.edu/fswiki/FsTutorial/LongitudinalTutorial_fr... and https://surfer.nmr.mgh.harvard.edu/fswiki/LongitudinalTwoStageModel
Best, Martin
On 01/30/2014 09:18 AM, amirhossein manzouri wrote:
Hi, Would you please advise if it is possible to do longitudinal statistical analysis within a group with two time points in Qdec. And if it is not possible in Qdec how I suppose to do it?
Best regards, Amirhossein Manzouri
Freesurfer mailing listFreesurfer@nmr.mgh.harvard.eduhttps://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
-- Martin Reuter, Ph.D. Assistant in Neuroscience - Massachusetts General Hospital Instructor in Neurology - Harvard Medical School MGH / HMS / MIT
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