Dear Ioannis,
Gousias, Ioannis schrieb:
> Dear Dr. Ashburner and SPM Members,
>
> Using the segment option in SPM5 I get the c1, c2, c3 files, which
> contain information on the probabilities of each tissue class.
>
> Is there a way to combine these files into just one file containing
> the probabilities of all tissue classes?
>
Do you mean p(c1)+p(c2)+p(c3)? Than you can do it with ImCalc selecting
files c1, c2 and c3 as input and the expression 'i1+i2+i3'.
> Also, if I threshold these files (e.g. 50% threshold), I create masks
> for each tissue class. Is there a way of adding these files to one
> file where each tissue type would be attributed a different integer
> value, e.g GM=0, WM=1, CSF=2? Also, how can I make an estimate for
> possible errors?
>
Again you can use ImCalc selecting the mask files as input and using
expression 'i1*0+i2*1+i3*2'.
But I think you should better use 'i1*1+i2*2+i3*3' otherwise you will
not be able to distinguish voxels outside the brain from white matter.
First you have to ensure, that the masks are not overlapping (e.g. with
'i1+i2+i3' and looking the maximum).
> Thank you in advance for your concern.
>
> Kind regards,
> Ioannis Spyridon Gousias
> MRC - Clinical Sciences Centre
> Imperial College London
> Hammersmith Hospital
> W12 0NN
Hope that helps,
Michael.
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Dr. Michael Erb
Sektion f. experimentelle Kernspinresonanz des ZNS
Abteilung Neuroradiologie, Universitaetsklinikum
Hoppe-Seyler_Str. 3, D-72076 Tuebingen
Tel.: +49(0)7071/2987753 priv. +49(0)7071/61559
Fax.: +49(0)7071/294371
e-mail: <[log in to unmask]>
www: http://www.medizin.uni-tuebingen.de/nrad/sektion/
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