[Freesurfer] Question longitudinal study about treatment effect with change of scanner and head coil?

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Dear experts,

I am reviewing a study that proposes a longitudinal study in patients across several years on the effect of medical treatment in terms of fcMRI and DTI-connectivity measures.

However, in several but not all patients, the scanner was upgraded from Trio to Prisma and the head coil was changed from a 12 to a 20-channel. Every patient had the upgrade at another time point.

I would like to hear your opinion on this. In my experience, the scanner upgrade and especially the head coil upgrade heavily affected the images.

So I have fundamental doubts about the feasibility. What would be the conditions under which it could be acceptable?

Thank you in advance! Best, Markus