Hi Barbara,
Sorry for the late response.
- the type of sequence does not matter much as long as the contrast between gray and white matter is good.
- the resolution is important, because you need to be able to see the internal thin layer of white matter in the hippocampus to be able to infer its internal structure; otherwise, the segmentation of the internal boundarie will indeed be dominated by the prior knowledge, rather than the intensities.
- the algorithm operates at 0.33mm (isotropic) resolution; the segmentation is provided both at that resolution and at 1mm isotropic (FS space); please see the details in the wiki:
https://surfer.nmr.mgh.harvard.edu/fswiki/HippocampalSubfields
If you send me the T2FLAIR and T2STIR images for a sample subject, I can take a look and give you more accurate answers ;-)
Cheers,
Eugenio
Juan Eugenio Iglesias
Postdoctoral researcher BCBL
www.jeiglesias.com
www.bcbl.eu
Legal disclaimer/Aviso legal/Lege-oharra: www.bcbl.eu/legal-disclaimer
From: "Barbara Kreilkamp" <bakk.hbg@googlemail.com>
To: "Freesurfer support list" <freesurfer@nmr.mgh.harvard.edu>
Sent: Friday, April 22, 2016 5:28:44 PM
Subject: [Freesurfer] hippo subfield segmentation new beta version (version 6)
Dear all,
Would you please help me on this one?
Thank you,
best wishes,
Barbara
-------- Forwarded Message --------
Dear all,
I've been reading the manuscript on version 6 freesurfer hippocampal
subfield segmentation "A computational atlas of the hippocampal
formation using ex vivo, ultra-high resolution MRI: application to
adaptive segmentation of in vivo MRI"
Can you please tell me if the type of sequence (e.g. coronal T2FLAIR vs
T2STIR) and voxel sizes of .4x.4x2mm^3 vs .4x.4x4mm^3 really make a
difference for this multi-modal algorithm?
I previously ran recon-all on 1mm isotropic T1-w scans all with similar
contrast.
It seems that the mesh fitting in version 6 is driven by the relation of
the subfields to each other rather than by contrast or signal
intensities; and also I notice the algorithm brings everything to
isotropic space anyway.
Is this correct?
Do you see a major methodological issue when using T2FLAIR (.4x.4x4mm^3)
and T2STIR (.4x.4x2mm^3) subfield volumes together?
Thank you very much,
Best wishes,
Barbara
P.s. as a side-note, I've not noticed any major differences in subfield
segmentations visually, when comparing segmentations via these two
different T2 scans.
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