Hi Stephan,
yes, you are right. The rendering is performed in the original orientation.
So, using non normalized data, you can flip the output image, for example,
within every paint program to get the right orientation.
An other solution is, to flip the images during the converting step from
DICOM
to Analyze. A lot of converting programs are having the option of a
left-right flip.
But attention, if you decide to normalize these data later, you have to
change the defaults for the normalization.
Good luck,
Karsten
----------------------------------
Karsten Specht
fMRI Section
Department of Neuroradiology
Medical Centre Bonn
Spessartstrasse 9
53119 Bonn
Germany
Phone: ++49-(0)228/90 81-178
Fax: ++49-(0)228/90 81-190
E-Mail: [log in to unmask]
WWW: http://www.mcbonn.de/Praxis/praxis15/fmri1.htm
> -----Ursprüngliche Nachricht-----
> Von: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]]Im
> Auftrag von [log in to unmask]
> Gesendet: Montag, 11. März 2002 20:55
> An: [log in to unmask]
> Betreff: orientation after rendering
>
>
> Hi,
>
> I have a problem with rendered unnormalized fMRI activations.
> Below are the steps how the data were analyzed:
> 1) The original EPI and structural images are defined according
> to the radiological convention (L=R).
> 2) Realignment and coregistration is carried out (none of the
> images is normalized).
> 3) The design matrix is specified and the results are displayed
> as t-maps. The obtained functional activations are ok and are
> defined according to radiological convention.
> 4) The 3d structural image is segmented.
> 5) Via the "render" button, the "extract brain" option is carried out.
> 6) The activations are superimposed on the rendered brain
> surface. However, this map is wrong since the activations are
> left-right inverted. How can I fix this problem? Is there an easy
> way to switch the left-right symmetry? I tried setting the
> defaults to L=R and also L=L, but this does not help here. My
> guess is that only if the normalization step is carried out the
> defaults option works.
>
> Thanks a lot for any suggestions.
> Stephan
> Stop wasting money on Inkjet and Toner Cartridges, Save 50% when
> you buy from GOink.com. Rated #1 on the web.
> http://www.goink.com
>
|