Can we compare MRS data acquired using different field strengths?

Dear experts,

What is your opinion on comparing longitudinal data from the same set of subjects at different time points but they were scanned in a different field strength? For example, a group of neonates was scanned at birth using a 1.5T scanner and they came back for a second scan using a 3T scanner.

Is it valid to compare the data if most parameters were the same in the protocol? (Metabolite measurements were in ratio of tCr or water)

Thank you,

Steve

This is probably going to be very difficult since relaxation times are different between field strengths (and they also change massively in the first few months of life). You’ll certainly see differences between time points, but I figure it’ll be near impossible to decide whether they are due to age effects or field strength effects.