Hi Wibeke
> Hello,
>
> can somebody tell me if it within SPM is possible either to:
>
> for each individual subject segment one brain structure as for example the
> cerebellum and retrieve the mean signal intensity from the cerebellum as a
> whole and thereafter divide each voxel in all the images with that signal?
>
not as such but you can use the automatic segmentation and then either
remove the cerebellum by hand or using a mask if you want to work in the
standard space
> for each individual subject draw ROI's in the images containing a spesific
> brain structure as for example the cerebellum, and retrieve the mean
> signal intensity from the ROI's and thereafter divide each voxel in all
> the images with that signal?
>
drawing ROI has to be outside SPM using Analyze or MRIcro - then using
ImCalc simply multiply the segmented image by the ROI (i1.*i2) so you
get as output only this structure - be careful with the interpolation
method though .. (with trilinear I use to take the absolute values then
put to 0 values under 0.5) - For more calculations as you want to do it
is simple matlab stuffs. Say for instance
mean(mean(mean(image(ROI==1)))) given that image is the all brain and
ROI is a binary image of the cerebellum gray matter then you have the
mean for image only where ROI = 1, i.e. the mean signal of the
cerebellum. Nothing automatic (button press) here but rather
straightforward.
Hope this helps
Cyril
--
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.
|