Freesurfer

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30088 discussions

average cortical thickness&intrinsic curvature index
by Liukarl 25 Mar '11

25 Mar '11

Hello, Freesurfer experts: We are extracting the average cortical thickness of each hemisphere for every subject using mris_anatomical_stats. We found that for one subject (attached below), the thickness measures are quite similar but the “intrinsic curvature index” differs drastically between left/right hemispheres. Will this curvature index affect the validity of our thickness measure? Thanks in advance Karl ***the left hemisphere mris_anatomical_stats -l lh.cortex.label -f subject1l.txt subject1 lh limiting computations to label lh.cortex.label. reading volume /usr/local/freesurfer/subjects/subject1/mri/wm.mgz... reading input surface /usr/local/freesurfer/subjects/subject1/surf/lh.white... reading input pial surface /usr/local/freesurfer/subjects/subject1/surf/lh.pial... reading input white surface /usr/local/freesurfer/subjects/subject1/surf/lh.white... structure is "lh.cortex.label" number of vertices = 157421 total surface area = 102165 mm^2 total gray matter volume = 290073 mm^3 average cortical thickness = 2.488 mm +- 0.694 mm average integrated rectified mean curvature = 0.170 average integrated rectified Gaussian curvature = 0.105 folding index = 4980 intrinsic curvature index = 592.3 ***the right hemisphere mris_anatomical_stats -l rh.cortex.label -f subject1r.txt subject1 rh limiting computations to label rh.cortex.label. reading volume /usr/local/freesurfer/subjects/subject1/mri/wm.mgz... reading input surface /usr/local/freesurfer/subjects/subject1/surf/rh.white... reading input pial surface /usr/local/freesurfer/subjects/subject1/surf/rh.pial... reading input white surface /usr/local/freesurfer/subjects/subject1/surf/rh.white... structure is "rh.cortex.label" number of vertices = 158401 total surface area = 102285 mm^2 total gray matter volume = 291519 mm^3 average cortical thickness = 2.482 mm +- 0.707 mm average integrated rectified mean curvature = 0.173 average integrated rectified Gaussian curvature = 0.299 folding index = 5756

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problem of correction for multiple comparisons in sarfece based analyses
by Habets P (SP) 25 Mar '11

25 Mar '11

Dear Freesurfer users, Which is to most preferably correction for multiple comparisons when investigating surface based cortical thickness changes between groups in smoothed data. Furthermore subjects between groups are related in other words not independent from each other. It is not clear for me whether FDR or cluster wise correction is feasible in highly smoothed and data that does not fulfill the criteria of independence. Best wishes, Petra Habets [cid:image001.jpg@01CBEAD1.5ACD2790] Petra Habets PhD-Student School for Mental Health and Neuroscience p.habets(a)maastrichtuniversity.nl <mailto:p.habets@maastrichtuniversity.nl> www.maastrichtuniversity.nl <http://www.maastrichtuniversity.nl> Vijverdalseweg 1, 6226 NB Maastricht P.O. Box 616, 6200 MD Maastricht, The Netherlands T + 31 43 368 8659 F + 31 43 368 8689 Note: the email addresses have changed! [cid:image002.jpg@01CBEAD1.5ACD2790]Please consider your environmental responsibility before printing this e-mail.

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The atlas specification
by Youngsang Cho 25 Mar '11

25 Mar '11

Hi, everybody. I am wondering the specification of the atlas which is used for surface registration. Please answer what kinds of subjects are used and how many subjects are used to generate the atlas included in Freesurfer. Or please tell me the link about the atlas specification. Sincerely, Youngsang Cho

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Vertex-by-vertex analyses within ROIS?
by Dalwani, Manish 24 Mar '11

24 Mar '11

Hello Freesurfers, We are interested in comparing cortical thickness in 2 groups. Due to small sample size (and thus less power), we are swaying away from whole-brain vertex analyses. Instead we would like to compare specific ROIs between two groups. We understand that we can get an estimate of average cortical thickness from each ROI. We fear that by comparing those estimates over a large ROI may cause it to be less sensitive in picking up a very small region of severe cortical thinning. Therefore, our questions are as follows: 1. Can we perform vertex-by-vertex analyses between groups but not on whole-brain and only on the specific apriori ROIs? 2. If we can do vertex-by-vertex ROI analyses, is there a reasonable statistical method to correct for multiple comparisons? Kindly advise! Regards, Manish Dalwani Sr. PRA Dept. of Psychiatry University of Colorado Denver Tel: 303-724-3185 Email: manish.dalwani(a)ucdenver.edu

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N3 correction issues
by Nandita Vijayakumar 24 Mar '11

24 Mar '11

Hi all, We are processing longitudinal structural MRI data on Freesurfer 5. 0. As our images have some intensity problems, we were running an N3 correction outside of FreeSurfer using a mask in order to maximize this step (as per recommended by Boyes et al., 2008). We first ran autorecon1 and then used the brainsmask.mgz as a mask for the N3 correction, using the following steps. mri_convert orig.mgz orig.mnc mri_binarize --i brainmask.mgz --min 1 --o binmask.mgz* mri_convert binmask.mgz binmask.mnc* mincnorm orig.mnc orig_norm.mnc nu_correct -mask binmask.mnc -distance 50 -iterations 1000 -stop 0.0001 -shrink 2 -fwhm .05 orig_norm.mnc nu.mnc mri_convert nu.mnc nu.mgz* This nu.mgz was then fed into freesurfer and autorecon1 was run over again without nuintensity correction. However, during this step, many of our scans are crashing, with the T1.mgz being very dark. When the same scans were run through Freesurfer with the nuintensitycor-3T flag (without using a mask), there were no crashes. Do you have any advice on why the N3 correction using the mask is crashing when re-running autorecon 1? Should we be using different nu_correct parameters to help the process? Thanks for your help! Nandi

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Fwd: fMRI and anatomical T1 overlaid
by leonardo kay 24 Mar '11

24 Mar '11

Thanks Doug. After doing reg-feat2anat , I checked the registration and overlaid zstat file: tksurfer subjectid rh inflated -overlay featdir/rendered_thresh_zstat1.nii.gz I have attached an image of tksurfer interface . I'm not quite sure about what blue and red clusters mean. They are suposed to be activations, but I'm not watching the same in FSL-view. Could you give me a hand please? Am I using the right stat file? Thanks in advance best regards. ---------- Forwarded message ---------- From: Douglas N Greve <greve(a)nmr.mgh.harvard.edu> Date: 2011/3/23 Subject: Re: [Freesurfer] [Fressurfer] fMRI and anatomical T1 To: leonardo kay <leonardo.kay(a)gmail.com> Cc: freesurfer(a)nmr.mgh.harvard.edu There is a tutorial on this on our wiki. Basically, you need to run reg-feat2anat to get a registration file, then run tksurfer passing it the registration file and the stat volume as the overlay. doug leonardo kay wrote: > Hi all > > Can anyone help me overlaying fMRI activations from fsl on a anatomical T1 > volume in freesurfer. > Is there any previous format conversion to do before? > > Thanks in advance > best regards, > > -- > Leo Kay. > > ------------------------------------------------------------------------ > > _______________________________________________ > Freesurfer mailing list > Freesurfer(a)nmr.mgh.harvard.edu > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer > -- Douglas N. Greve, Ph.D. MGH-NMR Center greve(a)nmr.mgh.harvard.edu Phone Number: 617-724-2358 Fax: 617-726-7422 Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting FileDrop: www.nmr.mgh.harvard.edu/facility/filedrop/index.html The information in this e-mail is intended only for the person to whom it is addressed. If you believe this e-mail was sent to you in error and the e-mail contains patient information, please contact the Partners Compliance HelpLine at http://www.partners.org/complianceline . If the e-mail was sent to you in error but does not contain patient information, please contact the sender and properly dispose of the e-mail. -- Leo Kay.

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parametric modulator with FS-FAST
by Yuko Yotsumoto 24 Mar '11

24 Mar '11

Hi, I am wondering whether it is possible to use "parametric modulator (SPM term)" in FS-FAST. For example, say I have 4 experimental conditions. These conditions are not independent. Conditions 1-4 are determined post-hoc by subjects responses - for example, attractiveness judgements. Condition 1 for least attractive, condition 4 for most attractive.. and so on. Instead of making contrasts for each condition, I'd like to find areas that show linear relationships (= % signal changes) with the regressors (=attractiveness judgements). I heard there is a way to do this with SPM, but I'd like to do this with FS-FAST. I found this post in the archive, but I need some more info. http://www.mail-archive.com/freesurfer@nmr.mgh.harvard.edu/msg14181.html Thanks! Yuko Yotsumoto ----------------------------------- Yuko Yotsumoto, Ph. D. Associate Professor The Global Centers of Excellence Program, Keio University TEL:011-81-3-5427-1156 x 23851 e-mail: yukoyy(a)a7.keio.jp HP : http://web.keio.jp/~yukoyy/ ------------------------------------

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isxconcat-sess question
by SK 24 Mar '11

24 Mar '11

Hi, Is there a way to use” isxconcat-sess” to average monkey fMRI data? i.e. I have two groups of monkeys (say, test and control groups) and I want to do group analysis on their data.. Regards, krishna

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ROI-based fixed effect analysis
by ye xiao 24 Mar '11

24 Mar '11

Hi everyone, Is there any way to do ROI-based fixed effect group analysis in Freesurfer? I want to get the average ces and cesvar (fixed effect) in a specific ROI. Can I just average the gamma and gammavar that in the osgm folder after I ran the voxel-based ffx group analysis in that ROI to get those values, if I have a group data defined ROI? And how to average the gammavar in a ROI? Just mean(gammavar), or sqrt(mean(gammavar^2))? Thanks very much for the answers. regards, Qi Zhu Laboratorium voor Neuro- en Psychofysiologie K.U.Leuven Medical School

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data preparation for SVM classification
by Alexander Ivanov 24 Mar '11

24 Mar '11

*Dear Freesurfers,* Could you please suggest me the best way to prepare structural data for SVM classification? I googled, searched the archives - there're no examples of such preparation using freesurfer algorithms (to my knowledge)... Thank you beforehand. --- *Regards,* *A. Hasfatin*

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