Dear Layla, 

My previous answer about considering different contrast from the same study as separate studies only works if the group of subjects of comparison is not exactly the same (eg. two different groups of patiens against the same group of controls). My apologizes for that. 

The new version of SDM doesn't allow to combine this kind of images; so if the group of subjects is the same in all contrast for a study, you should choose the one that best fits your criteria.

Kind Regards,
Lydia