Hi Sinead
I agree with Jorge - there is bound to be a substantial scanner effect. You might be better off keeping the data separate and treating the 3T as a confirmatory study.
cheers Bruce
On Mon, 18 Feb 2013, Jorge Jovicich wrote:
Dear Sinead,
we found global significant differences in thickness between 1.5T and 3T, in a group of subjects that was scanned at both scanners (http://www.ncbi.nlm.nih.gov/pubmed/16651008). I think that nothing stops you from doing the analysis, but maybe model in a field effect to asset it in your own data.
Cheers,
jorgeOn 18/02/2013 16:32, Sinead Kelly wrote:
Dear members,
I would like to get your opinion on this issue - I have a dataset of over 400 subjects but under half of this data was acquired on a 1.5T scanner and the rest was acquired on a 3T scanner. Would it be acceptable to conduct cortical thickness analysis on the combined dataset? From reading the literature it seems that this is not a major problem but I just wanted to get some more thoughts on this.
Thank you for your help,
Sinead
-- Sinead Kelly Neuropsychiatric Genetics Group Trinity Centre St. James's Hospital Dublin 8