Hi Fred,
your processing looks fine, but are you sure this is not only an
artifact when displaying the image? Try changing the interpolation from
bilin to Sinc (lower right in the graphics window or via the context
menu) and see if it is still there (or look at the image in MRIcron).
You changed the voxel sizes during normalization, so some interpolation
(and consequently, data degradation) is to be expected, but it should
not be too bad. If you blame segmentation, check the normalized
segmented tissue maps: with the higher resolution, you should be able to
see the problems there if segmentation goes wrong.
Best,
Marko
Fred Sanders wrote:
> Hi SPM experts,
>
> I recently preprocessed some images and after going through the
> preprocessing steps, I discovered a grid like artifact in the EPI
> images. The artifact is NOT there in the un-preprocessed images, so it
> must be something that I am doing in the preprocessing steps. The steps
> I took were:
> realign:estimate
> coreg: shifting the anatomical to the EPI space
> Segment the coreg anatomical
> normalize write - Subj to MNI (based on the parameters from the segment
> step)
> Smooth 8 FWHM.
>
> Using the segment step to generate the normalization parameters is new
> for me and I am wondering if artifact somehow arose in this step.
>
> I've attached an imaged with an example of the artifact I am referring to.
>
> Any suggestions?
>
>
> Thanks so much!!!
>
> Fred
>
--
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Marko Wilke (Dr.med./M.D.)
[log in to unmask]
Universitäts-Kinderklinik University Children's Hospital
Abt. III (Neuropädiatrie) Dept. III (Pediatric neurology)
Hoppe-Seyler-Str. 1, D - 72076 Tübingen
Tel.: (+49) 07071 29-83416 Fax: (+49) 07071 29-5473
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