Thanks a lot for the ideas, Bruce!
On Monday 12 January 2009 23:16:30 Bruce Fischl wrote:
Hi Martin,
for the MS study we were *very* careful to make sure that the white matter in the regions of detected effect was normal appearing, so I don't think it explains the thinning we saw.
I see! But there still could be places of significant cortical thinning and subcortical WM disease, which would be hard to spot on the T1 only? In this In situations like this, multispectral segmentation may be able to bring some more insight.
As for the effect you are seeing, you'll need to look through your individual subjects to see if this is the case. Do you have any T2 or PD data for the same subjects? You could look
That's a good idea for non-radiologist like me! ;) I'll check the other contrasts for the next suspicious results!
at those for the suspicious ones to distinguish damaged wm from gray matter. David Salat has thought about this much more than I have, and may have more to add.
cheers, Bruce
Thanks a lot,
Martin
On Mon, 12 Jan 2009, Martin Kavec wrote:
Hi,
I have been running quite a few clinical subjects (close to 300) through FS pipeline and comparing cortical thickness from parcellated cortex for each individual subject to its agematched controls. The subject clinical symptoms are not specific, ranging from amnesia, reduced ability to generate words, confusion, ...
Every now and that I see that the cortical thickness is suspiciously higher than STD of the controls even if there are no leftovers after brain extraction (I specifically verify it, and if necessary do the corrections). In the vast majority of these cases I also find lower total white matter volume.
I am speculating, if possible subcortical WM disease (as detected by reduced total volume of the WM) may come into the play. If subcortical WM gets darker, near the intensity of the GM, the cortical thickness may be overestimated. Could anybody comment on this idea?
I suppose there is no way of correcting this. At the same time I wonder, whether cortical atrophy in MS assessed by the FS is accurate. The cortical atrophy reported in MS by FS methods (Sailer2003) was highly focal, and I am wondering if such atrophy can reflect the wide range of disables and clinical symptoms.
I would appreciate any comments to my thought.
Best,
Martin _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer