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Hi Alberto,

In the current implementation the volume reported in the table is simply
the sum of the lesion posterior probabilities, i.e., it is not affected by
the threshold used to create the crisp segmentation result for the lesions.
A few months ago Stefano Cerri wrote some code to correct this behavior
(and apply different thresholds without having to re-run everything from
scratch), but it never made it into the repository (my fault).

You can get the behavior you want/expect by counting the number of voxels
assigned to lesions in the seg.mgz file - there is a ready tool for that in
FreeSurfer but I don't remember off the top of my head what the correct
command is (a search on the mailing list should be able to reveal it)

You'll also need to know the label number in the FreeSurfer lookup table
for lesions - perhaps Stefano can tell you what it is (?)

Koen


On Thursday, July 1, 2021, Alberto Del Cerro Leon <[email protected]>
wrote:

>         External Email - Use Caution
>
> Hello FreeSurfer team, I have a question about SAMSEG thresholds. I am
> analyzing the vascular lessions aplying several thresholds. I would expect
> that lower thresholds results in lower volumes but dont seems like that.
> What is the reason?
>
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