I'd suggest checking first what kind of values you're putting in. Try
DISPLAY and click around in your input images - the actual voxel values
will be shown. If your images have a range of say 20-50 then a threshold
of 100 will leave no voxels to be analysed, and you'll get "no inmask
voxels".
Hope this helps,
Alexander
-----Original Message-----
From: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]]
On Behalf Of Silke Matura
Sent: 25 February 2008 07:17
To: [log in to unmask]
Subject: [SPM] setting the threshold for vbm
Hello,
since nobody answered the question I posted last Friday, I try again:
I am trying to do an unpaired two sample t-test comparing grey matter
volumes of mci patients with that of healthy controls. Segmentation was
done
using the vbm5 toolbox provided by Christian Gaser.
In the "specify files" command, I entered the segmented grey matter
volumes
(m0wc1anatomy_HMRF.nii) of each group. I selected "absolute threshold
masking" and tried to enter a value of 0.05. The default value is 100. I
could not change that value. When I try to do the stats, I get an error
message: "no inmask voxels".
What did I do wrong? Why isn`t it possible for me to set a threshold ?
I would greatly appreciate your help
Silke Matura
Brain Imaging Center Frankfurt am Main
|