Thanks Martin for your reply, I am agree with you on point 1. What would you say in the case that we are interested in rates of decline from baseline to 12 months, but besides 6 months follow-up we also have 24 months?. Here I see more conceptual problems. In an hypothetical context of severe atrophy from 12 to 24 months, adding the 24 mo follow-up perhaps difficult registration more than improves it. What do you think?
Thanks a lot Best Daniel Hi Daniel, 1. yes. But why not include 6 month in your study if you have those scans??? You will get much more reliable slope estimates with 3 time points compared to 2, so including that time point will not only help for the image processing part, but also in your statistics (you gain power). 2. I am not familiar with the mprage flag and think it mainly affects the normalization. If you are sure you need it, then also add it to the -base and -long runs, just to be safe. best, Martin On 01/29/2014 09:08 AM, Daniel Ferreira wrote: Dear experts, I have two questions regarding the longitudinal stream: - I am including Baseline and 12 months follow-up in my study. However, I also have 6 months follow-up. I wonder if it is conceptually right to include these 6 months scans in template creation with the idea of increasing registration. - I am applying the -mprage flag in the crossectional first step. Should I use it in the -base and -longs steps too? Thanks very much Daniel Ferreira
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