open-discussion > VBM results interpretation
Jun 11, 2012  07:06 PM | Tanmay Nath
VBM results interpretation
I am trying to learn the VBM toolbox of SPM and I have strictly followed all the instructions from VBM8 manual( for Gray matter(GM) white Matter(WM) and Cerebro  spinal fluid(CSF) segmentation. I am trying to look at the difference in GM volume for 2 groups.

For the segentation, i have used all the defaults in Estimate and Write options in VBM8. After i have done the segmentation, i also used the "check data quality" to check my segmentation results. After smoothing, I used the 2 sample T test as my statistical model. I have strictly followed the manual for defining the parameters in this model. After running this model, i find that I have got a SPM.mat file in my analysis directory. After i Estimate my statistical model, I find that following images are generated in my analysis directory:
1. beta_0001.hdr
2. beta_0001.img
3. beta_0002.hdr
4. beta_0002.img
5. con_0001.hdr
6. con_0001.img
7. con_0002.hdr
8. con_0002.img
9. con_0003.hdr
10. con_0003.img
11. con_0004.hdr
12. con_0004.img
13. mask.img
14. mask.hdr
15. ResMS.hdr
16. ResMS.img
17. RPV.hdr
18 RPV.img
19. spmT_0001.hdr/img
20  SPMT_0002.hdr/img
21. SPMT_0003.hdr/img
22. SPM_0004.hdr/img

Also, when i define the contrast for group A vs group B (-1 1) and set the p value to  0.001(unc), then i find that the brain regions where i find significant difference in gray matter are not properly registered. Also, when i try to see only the brain for group A, I find that the brain is way out of the box and is not properly registered(I guess).
I have attached the images for your further understanding.
Following are my queries:

1.I am curious to know what these images mean which are generated after i have finished with the Estimation of my model.
2. Why am i facing this problem of getting improper results when i am strictly following the tutorial.Also, how to fix this problem.

Please reply and help


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VBM results interpretation
Tanmay Nath Jun 11, 2012
Ana Enea Nov 6, 2013
Ged Ridgway Nov 6, 2013
Ana Enea Nov 6, 2013
Ged Ridgway Nov 6, 2013
Ana Enea Nov 6, 2013
Rayana Braich Jul 18, 2012
Ged Ridgway Jun 18, 2012
Tanmay Nath Jun 19, 2012
Ged Ridgway Jun 19, 2012
Tanmay Nath Jun 19, 2012