[caret-users] Voxels size ??
donna at brainvis.wustl.edu
Mon Aug 22 07:56:21 CDT 2005
Dear Dr. Giffard,
I haven't tried this (on purpose, anyway), so I'm not sure, but here are
* Minor deviations (e.g., cubic 0.9) are unlikely to cause trouble, but
0.5mm voxels (e.g., colin27) almost certainly will. My sense is that
somewhere around .75-.8mm things would start to turn ugly.
* Parts of the algorithm that disconnect eye fat (skull), hindbrain, and
contralateral hemisphere (corpus callossum cut) are most likely to be
vulnerable to significant deviations from cubic 1mm voxel dimensions,
because they use landmarks that are based on number of slices from the
anterior commissure along each axis. (Someday, we hope to improve the
way these routines work.)
* Any resulting surface probably will need to be scaled (using Surface:
Transform) accordingly, so that they reflect true mm coordinates.
Unless John Harwell has made a change I don't know about (he's on
vacation for another week), then such scaling is required.
Of course, you can always resample to cubic 1mm, but I assume you have a
good reason for wanting to do otherwise. I'm sure you realize there are
ways to apply affine transforms to functional data (e.g., fMRI, CSM
sites, or cells) you want to map onto the surface.
Hope this helps,
On 08/22/2005 04:44 AM, Cyrille Giffard wrote:
>Please could you tell me if it is possible to use human anatomical MRI
>with an isotropic voxel size lower than 1 mm3 ??
>Thanks in advance for your answer
>Faculteit der Geneeskunde
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