Hello,
I am doing a VBM analysis to investigate grey matter differences between two dementia groups (dementia with Lewy bodies and Alzheimer's disease) and a group of healthy controls with SPM12.
I would like to combine data from two different datasets that have been acquired on the same scanner with a similar protocol.
However, in study A a resolution of 1x1x1 mm^3 was used for the structural scans while in study B the resolution of the structural scans was 1.2x0.938x0.938 mm^3. Both datasets contain data for both dementia groups and controls, but they are not completely balanced (study A: 15 controls, 13 AD, 12 DLB; study B: 16 controls, 16 AD, 18 DLB).
I have a few questions on how to do this:
1. How would you do a VBM analysis on scans with different resolution? As I understand it, all images would have to have the same size in order to create a common template for Dartel. So, is it OK to resample the images to a different resolution (e.g. resample all images to 2x2x2 mm^3) before running Dartel?
2. Is it a problem that I don't have the same number of patients and controls in both datasets? Should I add a covariate in the between-group design?
Many thanks in advance for your help!
Kind regards,
Julia
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