Mark,
The single slice is from a spin-echo EPI readout and the fMRI whole-head 4D
is from a gradient-echo EPI. Unfortunately, all the data have been
collected already so I don't have the option of taking a whole brain volume
for each subject using the spin-echo EPI sequence. I've tried playing
around with different registrations using FLIRT which have yielded the
following results:
1. spin-echo EPI to fMRI to MPRAGE using 6 DOF = no image
2. spin-echo EPI to fMRI to MPRAGE using 12 DOF = no image
3. spin-echo EPI to MPRAGE using 6/12 DOF = no images
4. MPRAGE to fMRI to spin-echo EPI using 6 DOF = single slice high res image
5. MPRAGE to spin-echo EPI using 6 DOF = single slice high res image
It seems like #4 is more accurate than #5 when overlaid with the original
slice but it is difficult to tell.
Is it defensible to register a high res image to a low res slice?? What is
actually going on here? And why isn't there an image when I try to use the
suggested registration sequence (slice to fMRI to high res / slice to high res)?
Susie
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