Hello Ji Hyun Kim,
although i'm not an expert, i've recently got an answer to a similar
question.
1. right
2. the intensity shows you an absolute (if you didn't scale images
before) value of tracer uptake or whatever in some point of the brain.
If you wish to extract individual values from a blob, you can use the
"V.O.I"
option. This gives you a circle VOI around the blob maximum, not
exactly the blob.
By the way, is there an option to treat a whole blob as VOI and
subsequently to extract individual average values exactly from the
blob area?
Sincerely,
Igor
On Fri, 5 May 2006 13:43:32 +0900
??? <[log in to unmask]> wrote:
> Dear SPM experts
>
> Actually I'm an SPM beginner and have a great interset in SPM
>analysis.
> I'm sutdyng a VBM analysis in a group of epilepsy patients.
> I have two questions.
>
> 1) I want to correlate the duration of illness with the brain
>regions of
> significant voxels, either positively or negatively.
> It seems reasonable that the duration of illness should be
>treated as
> covariate of interest and other
> variables(age, sex, total intracranial volume) be treated as
>confounding
> variables(covariate of no interest).
> I have chosen the multiple regression in the basic model (spm2)
>and
> constituted t-statistics as follows;
> 1 or -1 (duration of illness), 0(age), 0(sex), 0(total
>intracranial
> volume).
> Is it right??
>
> 2) When compared with controls subjects, several brain regions have
>survived
>FDR corrected 0.01.
> One of the these regions is the right thalamus (MNI coordinates,
>14 -26
> 8).
> Image intensity in this coordinate was extracted from each
>patients
> using each smoothed, normalized, and
> modulated image (using 'display' module in the spm2). What this
> intensity exactly stands for?
> If one patient has intensity of 0.54567 and the other, 0.45389,
>can I
> interpret that the latter has decreased
> thalamic volume in this coordinate??
>
> Thank you in advance for your kind answers.
>
> Sincerely,
> Ji Hyun Kim, Dr
> Dept of Neurology, Guro Hospitial
> Korea University School of Medicine
******************************
Igor Yakushev
Department of Nuclear Medicine
University of Mainz
Germany
phone 0049/6131/176739
fax 0049/6131/172386
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