TSNR: Gray vs. white matter

AFNI Message Board
1

Hi,

I’m not sure how to interpret the TSNR files… It seems like the greatest TSNR is within white matter, which seems unintuitive to me. I’m also not seeing low TSNR in regions where I would expect to (subcortical structures) and high TSNR in regions where I would expect to (cortex). Is this normal?

Thanks,
Aaron

2

Hi Aaron,

While the gray matter signal might be slightly higher
than that of white matter (and CSF even higher), the
gray matter also tends to have much more variance,
which leads to a lower TSNR.

  • rick