Resizing non-isometric voxels


#1

Hello experts,

I see that the new recommendations for fixel-based analysis include resizing voxels to 1.25mm prior to fod segmentation. Is this also the recommendation if voxels are not isometric? (My raw voxel sizes are 1.97x1.97x3).

Thanks in advance!

Rachael


#2

Hi @rgrazioplene,

Sorry for your post going unnoticed for so long. About your question: I’m quite sure people will have different opinions on this one, but personally, I would always resize to isotropic voxels. 1.25mm, or something thereabouts, for adults should do. The benefits will be less issues / biases during template building and registration, as well as tractography potentially thereafter, and even possibly the CFE mechanism in FBA. By the time your subjects are all in template space and non-rigidly warped anyway, you’ll have samples that come from many anatomical coordinates (vs original grid) for each subject anyway, so the impact of the original anisotropic resolution of the data effectively becomes less and less as you progress beyond the upsampling step. So in summary: personally, I would certainly resample to 1.25mm isotropic when dealing with data of e.g. 2x3x3mm voxels.

Cheers,
Thijs


#3

Thanks so much, Thijs. I did a little reading and came to essentially the same conclusion. Cheers!

Rachael


#4

No worries, sounds perfect! :+1: