Dear Sean:
Your voxel size is pretty coarse, and I suspect that means that you are
collecting data into a 64X64 matrix. For future studies you might want to
consider a 128X128 matrix with 3 degree angular sampling. This should
produce roughly 2mm voxels as long as you keep the radius of rotation as
close to the head as possible. Such data will give you greater flexibility
in using SPM not only at the spatial normalization stage, but also later in
choosing various smoothing kernels. We us the sampling scheme above (and a
3-headed scanner with about 7 mm spatial resolution) and are successful
using the SPM defaults for spatial normalization as well as gray matter
threshold (0.8).
-- Mike
Dr. Michael D. Devous, Sr.
Professor of Radiology
Nuclear Medicine Center
University of Texas Southwestern Medical Center
Dallas, TX 75235-9061
USA
phone 214 648-3315
fax 214 648-5641
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At 05:44 AM 5/17/00 , Sean Colloby wrote:
>Dear All,
>
>Could anybody possibly give me some advice regarding the spatial
>normalisation of SPECT imaging data. The images have a voxel size of
>5.4 x 5.4 x 5.4, and I have presently been using the default values
>given in SPM99.
>
>Are these the best variables to use?
>
>Which parameters have you found optimal for the spatial normalisation
>of SPECT data?
>
>I would be grateful if anyone can help.
>
>Thanks
>
>Sean Colloby.
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