Hi - sure, sounds like the best thing to do is to create an image
containing the % changes values and then use avw2ascii or probably
better avwmeants -showall.
First create the temporal mean of filtered_func_data using -Tmean in
avwmaths
If you take the relevant pe image from the .feat/stats directory, and
divide by the mean and * by 100 you'll get what you want as long as
the model was of height 1 - more more details you might want to look
at the featquery TCL source code.
Cheers, Steve.
On 31 Jan 2006, at 11:32, Michael Hanke wrote:
> Hi!
>
> I need to calculate an estimation of the % signal change of a large
> number of (individual) voxels for several individual stimulus onsets
> (event related design).
>
> I tried the following procedure:
>
> 1. Slicetiming and motion correction of the functional volumes.
> 2. Highpass and lowpass filtering.
> 3. Extract a range of volumes around a single stimulus onset
> (from 5 volumes before stimulus onset till 25 volumes after
> stimulus offset).
> 4. Mask extracted functional dataset with ROI mask.
> 5. Run feat on the dataset (square-wave stimulus modell with onset on
> the 5. volume).
>
> As I see it, I have two possibilities now: The exact way would be
> to use
> featquery for each voxel in my ROI (because I need the signal
> change in
> each voxel individually and not in the ROI mask as a whole). But this
> his some disadvantages for me. a) it takes a long time b) I need to
> extract the signal change value from an HTML file (or are they
> available
> somewhere else?).
>
> Because I want to process ALL signal change values toghether with a
> script
> I was looking for a way to get them a little easier. I tried using
> tsplot for every voxel in the ROI and calculated % signal change from
> the tsplot timeseries output for the full model. This works quite
> well,
> altough it is not as exact as the previous procedure. But it still
> takes
> some time.
>
> Is there a faster or easier way to get the sigbal change in individual
> voxels?
>
> Thanks in advance.
>
>
> Michael
>
>
> --
> GPG key: 1024D/3144BE0F Michael Hanke
> http://apsy.gse.uni-magdeburg.de/hanke
> ICQ: 48230050
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Stephen M. Smith, Professor of Biomedical Engineering
Associate Director, Oxford University FMRIB Centre
FMRIB, John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
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