There are a couple of reasons...
1) The subject has moved (or at least the realignment has estimated that
the subject has moved) out of the original FOV. Therefore this data is
no longer available in all scans.
2) When data is missing in some regions in some of the scans, it is set
to zero in that region for all scans. This is to prevent motion related
effects propagating from the edges due to smoothing.
Best regards,
-John
I have a series of images taken on one person: there are 20
repeats of 64x64x20 images. I have split the repeat images into
individual files, then used __spm8-pet-spatial-re-align-estimate
and reslice__ to align them. When I read in the aligned images,
the top and bottom slice of each image has no data (all the
voxels are 0). Can anyone explain why, and if it is possible to
get back to 20 slices.
--
John Ashburner <[log in to unmask]>
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