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30070 discussions

viewing group analysis results in tkmedit (3D) while using spherical space intersubject morphing
by raij＠nmr.mgh.harvard.edu 26 Jun '06

26 Jun '06

Hi FreeSurfers, A small group analysis question of fMRI data (fixed effects). The target brain is "fsaverage". I have resampled and averaged the stat maps across subjects in _spherical_ space using func2sph-sess / sphsmooth-sess / isxavg-fe-sess / stxgrinder-sess. Viewing the results on a "fsaverage" surface with tksurfer works fine, thanks. Now I would like to also view the mean functional maps in 3D space (tkmedit) on the "fsaverage" brain. This does not seem to work - obviously because the results were calculated in spherical space and were never resampled back to 3D space. Is there a way to resample the group average from sperical space to 3D space so that it could be viewed in tkmedit? Or is the only way to achieve something like this to recalculate the analyses entirely in Talairach space without using the spherical space? To make the results actually comparable between 3D (tkmedit) and surface-based (tksurfer) viewing, I think I should use the same type of space for intersubject averaging - preferably spherical in both cases. Hence, if a tool such as sph2func-sess exists (could not find it in the wiki), or there is a workaround, any suggestions would be very much welcome. Thanks, Tommi --- Tommi Raij, M.D., Ph.D. MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging Bldg 149, 13th St Charlestown, MA 02129 U.S.A.

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Difficulties with segmentation
by Jeffrey Spielberg 26 Jun '06

26 Jun '06

Hi, I had a couple of questions regarding cortical/subcortical segmentation- 1. In our cortical segmentation we keep getting what look to be inaccurate segmentation of the rostral and caudal acc. It looks some of what should be labeled as one of those two areas is getting labelled corpus callosum or "unlabelled subcortical" instead, sometimes fairly large chunks. Does this indicate any problem earlier in the processing stream, and is there anything that can be done to prevent this? If not I saw that both tksurfer and tkmedit can be used to edit the segmentation, what would be the easiest way to do this? 2. When registering a freesurfer anatomical to Feat output (using reg-feat2anat) the registration seems to be somewhat inaccurate. Registering brainmask.mgz to our example_func using flirt has given us a better registration so far. Since reg-feat2anat seems to use flirt in its registration I was wondering what the difference might be resulting from. Does reg-feat2anat use T1.mgz as it's reference scan, and if so is there any way to have it use brainmask instead, as that seems to give better results? Thanks, Jeff

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Re: Re: [Freesurfer] Finding ROI and average
by Joongnam Yang 26 Jun '06

26 Jun '06

Thanks, Bruce & Kevin, What I meant is that 1. I have an overlay image (FSL functional image overlaid onto Freesurfer inflated image). So, the image has both functional and anatomical in it. 2. I found an area of interest in the overlay image and I'd like to get (functional) statistics of that particular area regarding amplitude of activation. 3. I am asking if such a method is available on TkSurfer or TkMedit, or I should do some other methods. Thanks always. Nam. >>> Bruce Fischl <fischl(a)nmr.mgh.harvard.edu> 06/06/19 오후 2:57 >>> do you mean specifying it anatomically or functionall? You can do both. Anatomically you can use any of the cortical parcellation or subcortical segmentation units for this, or draw one yourself. On Mon, 19 Jun 2006, Joongnam Yang wrote: > Hi All, > > Is there a method of isolating an area of the overlay image (functional onto > anatomical) on Freesurfer as ROI and get the average of the amplitude of the > ROI? > > Any suggestions would be appreciated. > > Nam. > _______________________________________________ > Freesurfer mailing list > Freesurfer(a)nmr.mgh.harvard.edu > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer > > >

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questions about group analysis
by Lars M. Rimol 26 Jun '06

26 Jun '06

Hi, I have three questions: 1) Where can I find information on what the different output files of mri_glmfit represent, i.e. ar1.mgh eres.mgh rstd.mgh rvar.mgh These can all be plotted (Load Overlay) since they are .mgh files but they seem to rarely show any blobs (except with extremely liberal thresholding). Can they be used for QA of the analyses? What to look for? 2) What does gamma.mgh represent? I assume the sig.mgh is some kind of p-value distribution, is that correct? 3) What is the difference between the "Calculate identity matrix" and "No registration needed" options when loading Overlay? Do I need any registration if I do the statistical analysis e.g. in Matlab (after having done mris_preproc and mris_surf2surf) and export the results back to FS as mgh files? Or can I just choose No registration needed, given that registration did take place in the mris_preproc and mris_surf2surf steps previous to Matlab analysis? -- yours, LMR

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Volume estimates i Freesurfer
by Kjell-Inge Gjesdal 26 Jun '06

26 Jun '06

Members How do I get the actual numbers for the structural volumes after I have done the cortical and subcortical segmentations? Is the "norm" command needed to get the correct values? What are the units (ml or qubic cm/mm)? Is it possible to get a printable list? Thanks Kjell-Inge Gjesdal Sunnmøre MR-centre Norway

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Segmentation optimization
by Joao Pereira 26 Jun '06

26 Jun '06

Hello again, I've been having some problems with FS segmentation, especially around the temporal lobes, where there is a clear underestimation of the pial surface (and manual edits are not being too successful). The problem is clearly related to the poor resolution of the used images. Are there any parameters to change in order to optimise the segmentation process? Also, in order to evaluate the segmentation I want to use the grey matter segmented volume mask. Is it the ?h.ribbon.mgz files or should I consider something else? Thank you again. Joao Pereira

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recon-all error
by Anil Roy 25 Jun '06

25 Jun '06

Hello All, So I tried using recon-all to get a few parcellations stats from a minc file it but I'm getting the following error. Please could someone say how this can be rectified. Thanks. - Anil Roy. This is the command I'm giving: # recon-all -force -i /root/Desktop/F100.mnc -subjid F100 -sd /usr/local/freesurfer/subjects -autorecon3 This is the output. INFO: SUBJECTS_DIR is /usr/local/freesurfer/subjects INFO: /usr/local/freesurfer/subjects/F100 exists with -i, but -force specified. Deleting any previous source volumes Actual FREESURFER_HOME /usr/local/freesurfer -rw-rw-r-- 1 root root 30123 Jun 23 15:50 /usr/local/freesurfer/subjects/F100/scripts/recon-all.log Linux dhcp-129-105-146-155.speech.northwestern.edu 2.6.11-1.1369_FC4smp #1 SMP Thu Jun 2 23:08:39 EDT 2005 i686 i686 i386 GNU/Linux WM removal version /usr/local/freesurfer/subjects/F100 mri_convert /root/Desktop/F100.mnc /usr/local/freesurfer/subjects/F100/mri/orig/001.mgz mri_convert /root/Desktop/F100.mnc /usr/local/freesurfer/subjects/F100/mri/orig/001.mgz reading from /root/Desktop/F100.mnc... TR=0.00, TE=0.00, TI=0.00, flip angle=0.00 i_ras = (1, 0, 0) j_ras = (0, 1, 0) k_ras = (0, 0, 1) writing to /usr/local/freesurfer/subjects/F100/mri/orig/001.mgz... #-------------------------------------------- #@# Sphere lh Fri Jun 23 15:56:29 CDT 2006 /usr/local/freesurfer/subjects/F100/scripts mris_sphere ../surf/lh.inflated ../surf/lh.sphere $Id: mris_sphere.c,v 1.38 2006/02/08 00:17:40 nicks Exp $ $Id: mrisurf.c,v 1.441.2.3 2006/04/12 02:03:02 nicks Exp $ MRISread(../surf/lh.inflated): could not open file No such file or directory mris_sphere: could not read surface file ../surf/lh.inflated No such file or directory Linux speech.northwestern.edu 2.6.11-1.1369_FC4smp #1 SMP Thu Jun 2 23:08:39 EDT 2005 i686 i686 i386 GNU/Linux recon-all exited with ERRORS at Fri Jun 23 15:56:29 CDT 2006

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Re: [Freesurfer] The "5 mm limit" on cortical thickness?
by Graham Wideman 23 Jun '06

23 Jun '06

At 6/23/2006 06:57 PM, you wrote: >probably not. Check the intensity of the white matter underlying the gray >and see if it's significantly less than 110. If so, try putting a few >control points there (make sure they aren't in partial-volumed wm) Bruce: You would recommend this, even though the white boundary looks more or less in the right place? One incongruity is that the aseg segmentation gets the grey pretty much right, but the pial surface is way inboard. (I do understand that the aseg grey is not used to find the surface, it just *looks* like it should be smarter!). And probably we shouldn't strain this discussion too far at this point... we need to take a closer look given that the "5 mm" hypothesis is thrown out... Graham

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Re: [Freesurfer] The "5 mm limit" on cortical thickness?
by Graham Wideman 23 Jun '06

23 Jun '06

Bruce: Thanks for your reply -- >actually the limit is in the thickness measurement, not the deformation. >You can recreate the thickness files with mris_thickness -max $maxthick ... >if you want a larger value. What's going wrong? Well we're trying to guess why the pial surface is somewhat consistently (across subjects) positioned short of the actual pial surface in certain instances, notably frontal medial temporal, and some other locations. We had wondered whether it was because of such a limit. Graham

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The "5 mm limit" on cortical thickness?
by Graham Wideman 23 Jun '06

23 Jun '06

Probably Nick or Bruce: Could you confirm what I think I remember: that in the algorithm to move the surface out from the white position to the pial, FS is constrained by a 5 mm limit? -- Is this documented somewhere, with other details like what unwanted behavior this prevented, in what regions? -- Can this be disabled or set to a different value using a variable or somesuch? Thanks, Graham

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