Dear Eugenio,
I have a
couple of questions regarding the hippocampus subfields segmentation on
the dev FS 6.0 which I hope you could help me with.
We are
comparing the volumes of hippocampal subregions of patients and
controls, and we would like to be as consistent as possible with the
input so that the output reflects only the differences we expect to see.
The problem is that we have a large number of controls
but not all of them have the same sequences (T1, T2 or FLAIR) as the
patients. So our questions are:
If the T1s from some
subjects have a 1x1x1 resolution and others have 0.8x0.8x0.8 isotropic
resolution, do we have to create two groups of controls and patients for
each sequence? In other words, does the resolution of the T1 affect the
freesurfer segmentation in a way that we can't compare 1x1x1 with 0.8 x
0.8 x 0.8?
Also, we would like to use T2s or FLAIRs as
additional inputs to improve the results. Which sequence is preferably
recommended? In our case, most controls and patients have the same FLAIR
sequence, so to keep it consistent we would probably use FLAIR if
that's worth it.
Finally, we also have different T2s: some
isotropic, some anisotropic and partial cooverage of the brain, and some
anisotropic that are aligned to the hippocampus (resolution: 1x1x3,
best resolution on coronal slices). Considering that they are just
additional inputs, do they have to be consistent as well? In other
words, should we
only compare patients and controls that had the
same T2 sequence as additional input and same T1 sequence as main input,
or can we "mix and match" the additional inputs?