Hi - thanks for sending the results snapshot, though really we would
need to see the data to get a better idea of what's going on.
However, from looking at the snapshot, your ventricles are huge, and
the grey-white contrast is very poor, so this may be hard. You may
get much better results with just asking for 2-class segmentation (-c
2) and then the bias estimation should work fine anyway hopefully.
Cheers, Steve.
On 18 Jun 2007, at 09:17, Flavio Dell'Acqua wrote:
> Hi all
>
> We are starting using sienax to estimate ventricular CSF to study
> patients with hydrocefalus on standard spin echo T1 and T2 images
> matrix 256x256, 20 slices 5 mm thickness and 1 mm gap and we have
> some problem :
>
> Looking at debug results we observe that in restored data, after
> bias correction, ventricles are badly attenuated (central part of
> ventricles
> is now close to WM/GM intensity !) ...bias map is accordingly dark
> in ventricles and segmentation fails in this areas.
>
> We have tried different options with no results. In particular,
> after a search on fsl-list archive, we tried to disable bias
> correction using -l 1000
> but without improvements.
>
> Any suggestion ? Is there any chance to use this data? If it can
> help I can post a snapshot .
>
> Flavio
>
>
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Stephen M. Smith, Professor of Biomedical Engineering
Associate Director, Oxford University FMRIB Centre
FMRIB, JR 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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