Dear Marko and list,
According to the information posted below, I recently noticed the existence of segmentation difficulties in the deep GM, particularly in the putamen and thalamus, due to the lack of sufficient contrast with the surrounding WM of T1-weighted images (T1-WI).
Since this seems to be a known problem and probably there is not a solution for it, at least I would like to be informed if there are bibliographic references reporting it. So far, I couldn't find them...
Regards,
Antonio
-----Mensagem original-----
De: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]] Em nome de Marko Wilke
Enviada: segunda-feira, 18 de Dezembro de 2006 7:39
Para: [log in to unmask]
Assunto: Re: [SPM] increased pons intensity in white matter VBM
Hi there,
> Recently, I finished VBM analysis in my mTLE study.
Congratulations :)
> And I found increased white matter intensity in pons area.
> Because pons is classified into white matter in SPM segmentation,
> I thought this finding came from the neuronal loss (seizure damage) of pons.
You may want to be very careful in interpreting such findings as the
pons, as you say, is segmented into gray and white but it is among the
structures in the brain that are difficult to segment (as is the
thalamus). So it may be a case of segmentation leaning this way in a
patient and that way in a control. I do not know about your group sizes
but I have seen one badly segmented brain screwing up an analysis of >
100 brains (which I fortunately noticed before submitting :)
> Does it make sense?
Not to me but I am not an epileptologist. There certainly are
indications of pontine networks implicated in seizures but I would be
extremely careful before drawing such conclusions from a VBM study.
Best,
Marko
--
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Marko Wilke (Dr.med./M.D.)
[log in to unmask]
Universitäts-Kinderklinik University Children's Hospital
Abt. III (Neuropädiatrie) Dept. III (Pediatric neurology)
Hoppe-Seyler-Str. 1, D - 72076 Tübingen
Tel.: (+49) 07071 29-83416 Fax: (+49) 07071 29-5473
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