Be very careful when interpreting VBM results from stroke patients. The
segmentation in SPM may mis-classify white-matter regions where there is
stroke damage as grey matter, leading to an apparent increase in the amount
of grey matter in these areas. This makes the results difficult to interpret
in any meaningful way.
Best regards,
-John
> We are comparing two groups of stroke patients for differences in
> concentrations of gray matter. We have already normalized, segmented, and
> smoothed the images (with lesion masking). Since we are new to SPM, we are
> not sure about the statistical parameters that should be used. Can anyone
> review the parameters we used to see if they are correct, please!
>
> Basic Model:
>
> Two Sample t-Test
> scaling of overall grand mean: 100 (since we are interested in regional
> differences)
> threshold masking: no
> implicit mask: yes
> explicit mask: no
> global calculation: mean voxel value
> non-sphericity correction: no
>
> Results:
>
> mask with other contrasts: no
> adjusting p value: FDR
> p value: .05
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