 |
 |
Hi You might want to include the scanner as a confound in your model as was done in Interpreting scan data acquired from multiple scanners: A study with Alzheimer's disease NeuroImage, Volume 39, Issue 3, 1 February 2008, Pages 1180-1185 Cynthia M. Stonnington, Geoffrey Tan, Stefan Klöppel, Carlton Chu, Bogdan Draganski, Clifford R. Jack Jr., Kewei Chen, John Ashburner, Richard S.J. Frackowiak Note that scanner scanner effects could be massive relative to any effects you are looking for, that is why you might want to change your model. good luck sharon. On Mon, Nov 23, 2015 at 4:50 AM, Jess Reynolds <[log in to unmask]> wrote: > Dear SPM mailing list, > > I am undertaking a VBM study where data was collected on two different > scanners. The data set has clinical and control groups, with data from the > same number of participants from each of the two groups collected in each > of the scanners. When I run my grey matter group contrast analyses, is it > correct to run as a two sample t-test, with the scanner entered as a > covariate (scanner 1 entered as 0s and scanner 2 entered as 1s)? > > I have checked that there are no differences in the group contrasts by > running a full factorial design with two factors: 1) Group (2 levels), and > 2) Scanner model (2 levels), and there are no significant clusters for the > interaction between group and scanner. > > Thank you in advance for assistance. > Jess. > -- Sharon Gilaie-Dotan, PhD UCL Institute of Cognitive Neuroscience Alexandra House 17 Queen Square London WC1N 3AR Tel: +44-20-76791122 Mob: +972-54-4736181