If an MRI voxel is 1 cubic mm, that just means that the MRI can’t resolve anything smaller than that. If a significant proportion of that 1 cubic mm is made up of white matter, no matter the thickness of the white matter, you’ll see evidence of the white matter in that voxel.
An analogy would be a pixelated image. If you look at a pixelated image of somebody wearing a shirt with some symbol on it that has a lot of thin lines, but is a distinctly different color than the rest of the shirt, you will still see a contribution from that colored symbol in a pixelated image of the shirt.
qazit t1_jed8uu5 wrote
Reply to If MRI Voxels are 1mm^3 how can MRIs identify something as thin as white matter? by Zealousideal-Alarm37
If an MRI voxel is 1 cubic mm, that just means that the MRI can’t resolve anything smaller than that. If a significant proportion of that 1 cubic mm is made up of white matter, no matter the thickness of the white matter, you’ll see evidence of the white matter in that voxel.
An analogy would be a pixelated image. If you look at a pixelated image of somebody wearing a shirt with some symbol on it that has a lot of thin lines, but is a distinctly different color than the rest of the shirt, you will still see a contribution from that colored symbol in a pixelated image of the shirt.