Hi,
I'm new to FSL DTI analysis and am having trouble similar to that found in
the "Problems with eddy_correct and dtifit" post on this list. However,
the solution there does not appear to work for me. I have 5 b0 images plus
30 direction images, all in a data.hdr/.img. Directory listing is thus:
bvals data.hdr DIFFUSION-infodump.dat nodif_brain_mask.img nodif.img
bvals~ data.img DIFFUSION.mat nodif_brain_mask_mask.hdr
bvecs DIFFUSION.hdr flf nodif_brain_mask_mask.img
bvecs~ DIFFUSION.img nodif_brain_mask.hdr nodif.hdr
bedpost_datacheck (attached below) comes up clean, I believe. All file
creation was done on linux (no ^M isues here), and the bvecs are all
normalized. But, when I run dtifit, every dti.* output volume is empty
(all zeros). Any suggestions?
Note, for data.hdr/.img, I've tried 2 things. In one, data.hdr and
data.img were created via eddy_correct on DIFFUSION.hdr (which gave the
"Warning both reference and input images have an sform matrix set"). In
the other approach, I just copied DIFFUSION.hdr/.img to data.hdr/.img. In
either case, fslview suggests that data.hdr is fine, though timeseries
view on data.hdr shows the b0 images are substantially stronger signal
strength (by a factor of 2-5, depending on the voxel).
---- Results of bedpost_datacheck -----
.../diffusion/023> bedpost_datacheck ./
.//data
dim1 128
dim2 128
dim3 23
dim4 35
datatype 4
pixdim1 -1.7187500000
pixdim2 1.7187500000
pixdim3 6.0000000000
pixdim4 1.0000000000
cal_max 0.0000
cal_min 0.0000
glmax 0
glmin 0
origin1 67
origin2 83
origin3 12
file_type ANALYZE-7.5
.//nodif
dim1 128
dim2 128
dim3 23
dim4 1
datatype 4
pixdim1 1.7187500000
pixdim2 1.7187500000
pixdim3 6.0000000000
pixdim4 5.0000000000
cal_max 0.0000
cal_min 0.0000
glmax 439
glmin 0
origin1 67
origin2 83
origin3 12
file_type ANALYZE-7.5
.//nodif_brain_mask
dim1 128
dim2 128
dim3 23
dim4 1
datatype 4
pixdim1 -1.7187500000
pixdim2 1.7187500000
pixdim3 6.0000000000
pixdim4 5.0000000000
cal_max 127.0000
cal_min 0.0000
glmax 0
glmin 0
origin1 67
origin2 83
origin3 12
file_type ANALYZE-7.5
num lines in .//bvals
1
num words in .//bvals
35
num lines in .//bvecs
3
num words in .//bvecs
105
Any assistance would be greatly appreciated.
-best
Gary Strangman
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