Not yet, sorry. But it’s on my todo list.

Juan Eugenio Iglesias
Translational Imaging Group
University College London
http://www.jeiglesias.com
http://cmictig.cs.ucl.ac.uk/


On 6 Jul 2016, at 14:39, Hibert, Matthew Louis 
<mhib...@mgh.harvard.edu<mailto:mhib...@mgh.harvard.edu>> wrote:

Hi Eugenio,
Have you had a chance to look into the possibility of combining the -hires flag 
with the hippocampal subfield segmentation?

Thanks,
Matt
________________________________
From: 
freesurfer-boun...@nmr.mgh.harvard.edu<mailto:freesurfer-boun...@nmr.mgh.harvard.edu>
 
[freesurfer-boun...@nmr.mgh.harvard.edu<mailto:freesurfer-boun...@nmr.mgh.harvard.edu>]
 on behalf of Iglesias, Eugenio 
[e.igles...@ucl.ac.uk<mailto:e.igles...@ucl.ac.uk>]
Sent: Friday, June 10, 2016 3:36 AM
To: Freesurfer support list
Subject: Re: [Freesurfer] Hippocampal subfields segmentation - what is the 
voxel size of the input?

Hi Matt,
Bruce actually mentioned this possibility yesterday. Good to hear it doesn’t 
crash when you run it! That said, I need to go through the code, and make sure 
that data are handled the way they are supposed to: the fact that it doesn’t 
crash doesn’t directly imply that it is working properly. Hopefully I’ll find 
time to do this next week…
Cheers,
Eugenio


Juan Eugenio Iglesias
Translational Imaging Group
University College London
http://www.jeiglesias.com<http://www.jeiglesias.com/>
http://cmictig.cs.ucl.ac.uk/


On 9 Jun 2016, at 21:51, Hibert, Matthew Louis 
<mhib...@mgh.harvard.edu<mailto:mhib...@mgh.harvard.edu>> wrote:

Hi Eugenio,
Would it also be possible to use the -hires flag in the initial recon-all 
command to prevent the T1 from being downsampled and maintain the voxel size 
that the T1 was acquired at, and use that resulting recon for the hippocampal 
subfield segmentation?  I've tested this with MEMPRAGE scans acquired at 0.75mm 
isotropic and coronal T2 anisotropic scans acquired at 0.33mm in plane with 1mm 
thick slices, and the results look reasonable.  The "1mm" label files are 
correctly downsampled to 0.75mm instead of 1mm, and the higher resolution label 
files remain at 0.33mm resolution.

Thanks,
Matt

Stufflebeam Lab
Athinoula A. Martinos Center
Massachusetts General Hospital
149 13th Street, Room 1115S
Charlestown, MA 02129
________________________________
From: 
freesurfer-boun...@nmr.mgh.harvard.edu<mailto:freesurfer-boun...@nmr.mgh.harvard.edu>
 
[freesurfer-boun...@nmr.mgh.harvard.edu<mailto:freesurfer-boun...@nmr.mgh.harvard.edu>]
 on behalf of Iglesias, Eugenio 
[e.igles...@ucl.ac.uk<mailto:e.igles...@ucl.ac.uk>]
Sent: Thursday, June 09, 2016 2:36 PM
To: Freesurfer support list
Subject: Re: [Freesurfer] Hippocampal subfields segmentation - what is the 
voxel size of the input?

Hi Fernando,

Unfortunately, FreeSurfer does downsample the T1s to 1mm, and the subfield code 
assumes that the T1 comes from FreeSurfer… For the paper, I hacked the code to 
take advantage of multiple images with higher resolution, but it hasn’t been 
thoroughly tested and it’s not publicly available at this point.
That said, there are different things you can do at this point:
1. Use the T1+T2 as is (disadvantage: T1 will be resampled to 1 mm).
2. Use only the T2.
3. Use only the T1. To do this, you would use the T1 as additional scan on its 
own (i.e., the main and additional scans are the same, but the additional one 
won’t be resampled).
4. There might be a way (hack) of using both scans at full resolution. If you 
change the header of the T1 scan and specify that the voxel size is 1mm, no 
resampling will happen; FreeSurfer will believe that you’re dealing with a 
subject with a very large head. If you do this, you’ll also have to enlarge the 
voxel size of the T2 by a factor 1/0.7. Also, the resulting volumes will have 
to be divided by (1/0.7)^3 in order to correct for the “wrong” voxel size.

I hope this helps!

Cheers,

Eugenio

Juan Eugenio Iglesias
Translational Imaging Group
University College London
http://www.jeiglesias.com<http://www.jeiglesias.com/>
http://cmictig.cs.ucl.ac.uk/


On 9 Jun 2016, at 19:23, Fernando Pasquini Santos 
<fernandop...@gmail.com<mailto:fernandop...@gmail.com>> wrote:

Dear,

I have a doubt regarding the input T1 image used for the Hippocampal Subfield 
segmentation in Freesurfer 6.0 - 
https://surfer.nmr.mgh.harvard.edu/fswiki/HippocampalSubfields

In this documentation it says that I can use a standard 1mm T1 image or the 
same standard 1mm T1 image with an additional scan. However, I want to use a 
0.7mm T1 image as input, with an additional T2 scan. When I run the program 
with it, the output images (nu.mgz and orig.mgz) are downsampled to 1mm voxel 
size. So, I don't know if this happens just because of the recon-all program or 
if the segmentation is being done in the downsampled T1 image or in the 
original 0.7mm.

By reading the article "A computational atlas of the hippocampal formation 
using ex vivo, ultra-high resolution MRI: Application to adaptive segmentation 
of in vivo MRI" I saw that, in the methods section, the algorithm is used to 
segment 0.6mm T1 images. But is this possible to do in the Freesurfer package? 
Obviously, doing the segmentation directly on 0.7mm data would be better than a 
downsampled version to 1mm...

Thanks,

Fernando Pasquini Santos
PhD student in Dynamic Systems
fernandosan...@pitt.edu<mailto:fernandosan...@pitt.edu>
fernando.pasquini.san...@usp.br<mailto:fernando.pasquini.san...@usp.br>
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