Freesurfer February 2009

freesurfer@nmr.mgh.harvard.edu

86 participants
126 discussions

about segmentation
by Silvia biopanda 26 Feb '09

26 Feb '09

Hi, we are making changes in the aseg.mgz and we need to know how to erase a wrong pixels. we read in the tutorial that the button three erases, but it doesn't work.how can we do? cheers, SK

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Processing leaving out certain processing steps
by Lucas Eggert 26 Feb '09

26 Feb '09

Dear Experts, I would like to compare different processing procedures for the classification of gray matter. For this purpose, I would like to compare e.g. FreeSurfers default processing stream for subcortical labeling with the result that you get, if you leave out bias correction (nu_correct) in this processing pipeline, or replace N3 with another bias-correction algorithm. But, it appears to me, that the subsequent steps always look for the output-file of the previous processing step that would have took place in the default processing. So, my question is: How can I most efficiently leave out or replace single processing steps in FreeSurfer's default processing stream? Any help would be very much appreciated. All the best, -Lucas _______________________________________________________________________ DSL zum Nulltarif + 20 Euro Extraprämie bei Online-Bestellung über die DSL Freundschaftswerbung! http://dsl.web.de/?ac=OM.AD.AD008K15279B7069a

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standard error for betas
by Lars M. Rimol 26 Feb '09

26 Feb '09

Hi, I have fitted a glm with three different groups, using mri_glmfit (FS v4.0.3). I use the beta.mgh to get the adjusted means within an ROI, for each group. I'd like to make a bar or box diagram with the adjusted means/betas, but I'm not sure how to get the standard error of the betas so I can make error bars or a confidence interval. It seems that mris_anatomical_stats won't take the beta.mgh as input. Is there another way to do this in FS? Or will I have to do it outside FS? All my contrasts have only one vector, so each comparison should reduce to a t-test (according to the Wiki). In general, given the p (sig.mgh) and df of a t-test, I can get the t-value, and given the difference between the betas, the df and the t, I can get the SE. But I assume this is a little more complicated than that? I guess I can't use the rvar.mgh or rstd.mgh, since these are based on the whole model and not just the two groups. Which brings me to a related question: In mri_glmfit, when you have more than two groups in your model, and perhaps also e.g. age as a continuous regressor, and you set a contrast to compare two of the groups, does the variance estimate (SE) include the variance of all the variables, i.e. all groups that are in the model including the ones not included in the comparison + whatever covariates there may be? If so, isn't it really closer to a Tukey's or Scheffe's than an ordinary t-test? But back to my main question: Is there a way to get a measure of dispersion or confidence for the betas associated with each of the three groups in my analysis? (And if there is, I probably can't just average that measure across all vertices in the ROI, right?) Thank you! -- yours, LMR

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creating an infodump.dat file
by Dominique Jennings 25 Feb '09

25 Feb '09

Hi, I am trying to determine the b-values, number of directions and b0 volumes in a GE DTI data set. I know that unpackdcmdir creates an infodump.dat file, and that one can obtain these parameters from that file. I am using a slightly modified version of the 'dcmdir-info-ge' script (written by Doug Greve), but it doesn't automatically create an infodump file (at least, not yet). I would like to create a similar infodump file for these GE data. Does someone out there know how 'unpacksdcmdir' makes that infodump.dat file? Thanks in advance. Nicki

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Thickness histogram on labelled region only
by Pierson, Ronald K 25 Feb '09

25 Feb '09

I would like to look at the histogram of cortical thickness for the cingulate cortex because I am concerned that the edges next to the corpus callosum have very low thicknesses (and significant regions that are zero) that may be creating some interesting cingulate results we are seeing. I see there is a matlab script to look at the thickness histogram of the entire cortex, but is there a way to create a histogram for just one labeled region at a time? Thanks, Ronald Pierson Notice: This UI Health Care e-mail (including attachments) is covered by the Electronic Communications Privacy Act, 18 U.S.C. 2510-2521, is confidential and may be legally privileged. If you are not the intended recipient, you are hereby notified that any retention, dissemination, distribution, or copying of this communication is strictly prohibited. Please reply to the sender that you have received the message in error, then delete it. Thank you.

1 0

scatterplots in tkmedit
by Victoria Williams 25 Feb '09

25 Feb '09

Hello, I ran a GLM using a 4d skeletonized Fractional Anisotropy volume as my input into mri_glmfit with one variable. As this analysis is not surface based, I must open the results (sig.mgh) using tkmedit as an overlay. My goal is to open a scatterplot similar to that in tksurfer which shows the voxel value vs. variable score for each individual subject at a particular location. When I try to load the GDF file (the y.fsgd output in glmdir right?), it also asks for a registration file. I don't think there is a register.dat file as an output in the glmdir.... so, I was wondering what registration file it is looking for? Thanks for the help! Tori

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GLM Contrast
by Jeff Sadino 25 Feb '09

25 Feb '09

Hello, I am running the mri_glmfit and would like to doublecheck my contrast file. This is my fsgd file: MeasurementName thickness Class ctrl Class cd Class nc Variables age ed Input 040002_S04 nc 42.62 18 Input 040005_HG01 nc 45.26 15 Input 040008_S01 nc 26.92 16 Input 050015_S01 nc 46.65 12 .. .. .. with values for cd and ctrl as well. I want to see if there are differences in thickness between my control group and my cognitive deficit group after taking into account for age and education. This is my matrix file: 1 -1 0 0 0 0 0 0 0 for ctrl, cd, nc, ctrl age, cd age, nc age, ctrl ed, cd ed, nc ed Will this matrix file work for my hypothesis? It seems like if the last 6 are zeros, then it will not be taking age and education into account? And then also, since I have 90 subjects in all, will I need to correct for multiple comparisons? Thank you in advance, Jeff Sadino _________________________________________________________________ Access your email online and on the go with Windows Live Hotmail. http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_HM_AE_Access_022009

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question about spmregister-sess
by Srihasam, Krishna 25 Feb '09

25 Feb '09

Hi, I am trying to register my functional images with a high resolution anatomical image. I am getting a really bad registration. The anatomical image has the following stats: Dimension : 126x165x103 Voxel size : 1 x 1 x 1 Fov : 165 nFrames : 1 Orientation: RPI Primary Slice Direction : axial The functional image has : Dimension : 84 x 96 x 33 x158 Voxel size : 1.4583 x 1.4583 x 1.5 Fov : 84 nFrames : 158 Orientation: RPI Primary Slice Direction : axial I am using the following command to do the registration: "Spmregister-sess -sf sessid -df sesspar " It looks like something to do with the scaling factor. But, I have no idea how to change it. Any help will be welcome.. -Krishna

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Freesurfer Problem
by Naveen Kumar Yadav, Mr 25 Feb '09

25 Feb '09

Hi, I used Linux Red Hat 5 to install the freesurfer from your website. I followed the downloading and Installing steps as mentioned in your website. But when I tried to Test the Freesurfer Instalation it gave me the following message [inverse@localhost subjects]# tkmedit bert orig.mgz tkmedit.bin: error while loading shared libraries: libXmu.so.6: cannot open shared object file: No such file or directory. So I am wondering does it make difference if we download the latest Freesurfer software on Redhat 5 or Redhat 9. Is the error is due to linux version or is there is anyother problem. We used this Unix command to download the sofware on Redhat 5 ...freesurfer-Linux-rh9-stable-pub-v4.2.0.... Please let me know the solution. I will be thankful to you. Thanks Regards Naveen K. Yadav MSc Research Assistant Dept. of Ophthalmology McGill Vision Research McGill University Montreal, Quebec, Canada

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Freesurfer Problem
by Naveen Kumar Yadav, Mr 25 Feb '09

25 Feb '09

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Freesurfer February 2009