>Date: Mon, 26 Mar 2001 10:27:04 +0100
>To: mtwu <[log in to unmask]>
>From: Tina Good <[log in to unmask]>
>Subject: Re: VBM and posterior fossa
>In-Reply-To: <012201c0b58e$869db5c0$91c5a8c0@wumt2k>
>References: <[log in to unmask]>
>
>Dear Ming-Ting
>
>We have shown normal sex differences in the cerebellum (unpublished data)
and are currently looking at disease groups. Basically,you need
particularly high resolution structural scans with good grey/white
differentiation in order to segment cerebellar and brainstem structures
well. (see Deichmann et al NeuroImage 2000)
>The non uniformity correction is important for segmentation in this
region, partyicularly at the inferior limits of the coil) (I suggest using
the maximum non-uniformity correction option in SPM 99) (see also Ashburner
& Friston: VBM: The methods, 2000)
>
>If you are studying patients with marked atrophy, I would strongly suggest
using customised templates (created by normalising all the patients and
controls to the SPM template, then averaging and smoothing) I prefer using
grey and white matter templates rather than a whole brain template.
>
>I think it is important to exclude non brain voxels prior to normalisation
and segmentation, since many sigmoid sinus/jugular bulb, scalp and petrous
apex voxels survive on the grey matter images and lead to quite marked
error (see previous VBM reply to mailing list on automated brain extraction)
>
>I hope this helps
>with best wishes
>Tina
>
>
>
> At 08:40 26/03/01 +0800, you wrote:
>>Dear SPM group:
>>I would like to know if there are nay studies done on posterior fossa,
>>especially the cerebellum, using VBM?
>>Is there any known limitation of VBM in this area?
>>
>>*******************************
>>
>>PLEASE ALSO SEND A COPY TO
>>[log in to unmask]
>>
>>*******************************
>>Sincerely
>>Ming-Ting
>>======================================================
>>Ming-Ting Wu, MD. Department of Radiology
>>Kaohsiung Veterans General Hospital, Kaohsiung, 813, Taiwan
>>Tel: 886-7-3422121 ext 6205, 6235
>>Fax: 886-7-3468301
>>Mobile: 0920040712
>>----- Original Message -----
>>From: "Teri Franklin" <[log in to unmask]>
>>To: <[log in to unmask]>
>>Sent: Monday, February 26, 2001 9:54 AM
>>Subject: Re: VBM and the hippocampus
>>
>>
>>> Can someone please explain to me why gray matter changes in the amygdala
>>> (and hippocampus) cannot be identified using VBM and SPM99? I have read
>>the
>>> Woermann et al paper that describes visibly evident hippocampal damage in
>>> epileptic patients that was not detected using VBM. The authors reason
>>that
>>> small abnormalities are excluded due to normalization, segmentation, and
>>> smoothing. Although that makes sense to me - it doesn't make sense that
>>the
>>> hippocampal damage that could be seen with the naked eye could not be
>>> detected with this method. They also state that automatic segmentation
>>and
>>> voxel-by-voxel comparison of structural MRI is not suitable for
>>> investigating the amygdala and hippocampus. Is it just these two regions?
>>> Why just these two regions? I would greatly appreciate any references
>>or
>>> help in resolving this issue. Thanks all, teri-)
>>>
>>
>>
Dr Catriona Good
Clinical lecturer / Neuroradiologist
Wellcome Dept of Cognitive Neurology, ION
12 Queen Square
London WC1N 3BG
email: [log in to unmask]
phone 0207 8337485
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