Yes, this is caused by the large change in image resolution. We are
working on this for the next release, though you may find that editing
the script to insert a little spatial smoothing after the first
deprojection stage helps with this.
Cheers.
On 15 Feb 2008, at 20:18, Merry Mani wrote:
> Hello,
>
> I'm using TBSS to determine the areas of FA differences between
> two groups. I got an ROI of 99 voxels in MNI152 1mm space. I
> deprojected the ROI to the native space of 2x2x2mm of 120 x120 x60
> slices for my 40 subjects. I tried both trilinear and nearest
> neighbour interpolation. But I see big differences in the number of
> voxels that are getting deprojected to the native space for
> different subjects. Is that normal? What are the factors that affect
> the number of voxels that gets deprojected to native space? Is there
> anything that I can do to have approximately the same number of
> voxels for all subjects?
>
> T give you an idea, here are the number of voxels for different
> subjects de-projected using NN and trilinear interpolation from the
> above ROI.
> NN Trilinear
>
> 13
> 51
> 8
> 27
> 9
> 28
> 9
> 29
> 13
> 38
> 6
> 26
> 7
> 20
> 6
> 18
> 5
> 18
> 8
> 27
> 5
> 17
> 6
> 17
> 10
> 24
> 6
> 22
> 7
> 17
> 11
> 16
> 8
> 22
> 10
> 28
> 12
> 18
> 8
> 17
> 13
> 33
> 13
> 32
> 6
> 16
> 10
> 31
> 6
> 32
> 10
> 24
> 7
> 28
> 10
> 22
> 11
> 22
> 14
> 21
> 9
> 35
> 8
> 23
> 8
> 19
> 9
> 21
> 7
> 26
> 8
> 20
> 10
> 28
> 10
> 16
> 13
> 26
> 6
> 18
>
> Thanks,
> Merry.
>
>
---------------------------------------------------------------------------
Stephen M. Smith, Professor of Biomedical Engineering
Associate Director, Oxford University FMRIB Centre
FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
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