I’ve run the pipeline to estimate FC, FD, and FDC of my single-shell DWI data. Then, I decided to use ROIs (tracts including the uncinate, IFOF, ILF, SLF, corpus callosum) to extract mean FBA metrics per tract. I converted these binarized FSL ROIs to fixel space via voxel2fixel, where the output is a directory containing index, directions, and a [tract].mif file. When I view the output [tract].mif file (thresholded at 1), it looks to be in the right location. I did not threshold the mask after or during the voxel2fixel step since this mask was binarized beforehand. Then, as suggested in previous posts, I used the following command:
mrstats -mask [tract].mif -output mean [subj].mif.
Seems good so far? However, when I looked at correlations between tracts, they seemed unusually high. For example, in my sample, the correlation between FC of the left corticospinal tract and right anterior thalamic radiation is .97. Other correlations ranged from .69-.96. Do we expect FBA metrics to be highly correlated across tracts, where greater/lower FC in one tract is likely to be accompanied by greater/lower FC in other tracts? Or, could it be that my method of masking and extracting values is missing something?
Any advice is much appreciated.
All the best,