Hi John,
Your acquisition was apparently acquired with an oblique orientation, in
which case you expect there to be off-diagonal components in the q/sform
matrix in the nii header.
If T is your matrix, and
w1 = T*[i j k 1]' is the position of voxel index (i,j,k) in "world
space" and
w2 = T*[i j k+1 1]' is the position of voxel index (i,j,k+1)
then
norm(w1-w2) = 1.0,
which is exactly what you'd expect if the data at hand was collected
with a 1 mm isotropic spacing.
That is, any structural measures should be fine. When you display the
data in "Voxel space" you are showing it aligned with the original
acquisition axes. When you show it in "World space" you are rotating it
according to the matrix T.
cheers,
-MH
On Mon, 2012-04-23 at 04:07 +0100, John Smith wrote:
> -0.9988 -0.0287 0.0390 124.3288
> -0.0201 0.9785 0.2051 -97.2591
> 0.0441 -0.2041 0.9778 -13.5133
> 0 0 0 1.0000
|