hello SPM
we are testing a brand new GE 1.5 TE scanner with an fMRI sequence of
visual activation and rest (TE=3000ms, TR=60ms, 4 slices through
visual cortex x 128 x 128).
in the realignment stage we get the error that there is not enough
overlap in the images to find a solution. So we tried to look at the
images with "display" and "check reg". In check reg, a single black
box with no crosshairs appears in the display box and the error message
"matrix is singular to working precision" is given. In "display", again
a single image with no crosshairs - and the following error:
"error using chol-> matrix must be positive definite".
Our images are in .img format and are visualisable without problems
in analyze.
Any ideas? Is it possibly because we are using so few slices?
many thanks in advance
Chris Summerfield
psiquiatria i psicobiologia clinica
universitat de barcelona
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|