strange format after FunImgNormalizedSmoothedDetrendedFilteredCovremoved

Submitted by Timhahn on

 Dear all, 
I ran a seed-based connectivity analysis using DPARSF and REST. While all images look fine in FunImgNormalizedSmoothedDetrendedFiltered, after removing the covariates, they look strangely distorted (and are not in the usual shape of the whole-brain template anymore; I attached one of the files) in FunImgNormalizedSmoothedDetrendedFilteredCovremoved. I am not sure if this is a problem as the images in the FC folder are shaped ok again (the whole-brain mask I entered was applied).
Did something go wrong when removing the covariates or should the images in FunImgNormalizedSmoothedDetrendedFilteredCovremoved look that way?
Thanks a lot for your help.
Best,
Tim 
PS. Is there any way to use the newly added atlases in DPARSA also in DPARSF?

YAN Chao-Gan

Thu, 11/01/2012 - 21:49

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Hi,
 
The image is normal after regressing out covariates. For each voxel, the temporal mean will be zero after nuisance regression, thus you will no longer see the difference in mean intensity among gray matter, white matter and CSF. 
 
Also, you will see a clear boundary between voxels insider brain from those outside brain before regression. However, after nuisance regression, all the voxels were near zero, thus you will no longer see the boundary.
 
Most of the resting-state fMRI analyses (e.g., FC, ALFF, ReHo) were interested in the variation other than the mean, the temporal dynamics were still there within the "distorted" images.
 
In DPABI V2.1 and DPARSF V4.1, an option of “Add mean back” for nuisance regression is added. The mean will be added back to the residual after nuisance regression. This is useful for circumstances of ICA or task-based analysis.
 
Best,
 
Chao-Gan

 

 

Dear Experts,

I believe that I have the same exact question, but as the image is no longer available in the link from the original post, I just wanted to make sure that my uploaded image represents the image from the original post.  While all the images before covariate regression have voxels contained strictly within the brain, after covariate regression, the voxels are spread out as if they are in a different bounding box.  After running a group analysis, the voxels are then constrained within the brain again.

I just wanted to make sure that this was normal.  

Thank you!

Jason

 

 

 

 

 

 

 

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