Freesurfer

freesurfer@nmr.mgh.harvard.edu

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30089 discussions

ICV calculation error?
by Gabor Perlaki 19 Jun '12

19 Jun '12

Hi all, We use freesurfer 5.1.0 and we ran the recon-all on 100 subjects. We checked the talairach transform, skull strip the pial surfaces and the segmentations as suggested on Freesurfer Wiki. Everything seems to be fine, however, the ICV values from the stats/aseg.stats seem to be incorrect. The average value of ICV's is 1280 cc for men and 1108 cc for women, which seems pretty low. In 21 subjects from the 100 the ICV was even smaller than the supratentorial volume. The talairach transforms seems to be fine by visual inspection. 1. I think the wrong estimation of ICV value (because of the talairach transformation is not the best, although it seems right by visual inspection) won't affect the cortical/subcortical segmentations. Is it right? 2. What volumes should I sum to get an ICV, which is not estimated from the talairach transformation? 3. Is it a volume (other than ICV) reported by freesurfer, which can be used for correcting for overall head size? I'd appreciate an early reply. Thanks, Gabor

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position open
by Gennan Chen 18 Jun '12

18 Jun '12

Hi! We have an algorithm developer position open. Below is the job description. Although it stats in a very general term, the person will spend most of time working on freesurfer related algorithms and services. Experience in PhD or Post doc did count as long as it is related to algorithm development. Please send resume to me directly. Thanks Gennan Chen (gennan.chen(a)synarc.com) Engineering Manager, Engineering Department, CCBR-Synarc (www.synarc.com) Algorithm Development Engineer Analyzes, prototype, designs, programs, debugs, and modifies medical imaging processing algorithms used in clinical trials settings. Responsibilities: * Prototype, Design, develop, unit test and release medical imaging processing algorithms to support Synarc's business. * Work with end users to understand requirements. * Write and contribute to design specifications, installation guides and other technical documentation in accordance with Synarc best practices. * Work with other technical staff to support system installations, upgrades, and configurations of software. * Assist in training of users and creation of user manuals. * Ensure that systems are released in accordance with regulatory and Synarc standards. * Work with end users, other developers, software QA, product managers and software project managers to deliver applications, bug fixes and enhancements. * Use professional experience to provide creative, effective solutions to complex problems. Qualifications: Education: PhD in biomedical engineering, physics or computer science Experience: 4+ years of design and implement complex medical imaging algorithms in related fields such as registration and segmentation. Expert in Matlab and extending Matlab in C/C++ Experience in Freesurfer and related processing stream. Experience with DICOM standard Experience with cloud, cluster and other high performance computation environment. Experience with Java enterprise application development stack Experience with SQL and relational database Skills: Good problem solving, technical troubleshooting, organizational, interpersonal and team skills. Good written and verbal communication skills. ________________________________ This email message is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message. If you are the intended recipient, please be advised that the content of this message is subject to access, review and disclosure by the sender's Email System Administrator

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map ROI-based measures back to surface
by Leon 18 Jun '12

18 Jun '12

Hi, FreeSurfer experts I used mri_make_surface_parcellation and parcellated the brain into 200 ROIs. Then some measures were derived based on the ROIs and now I have 200*1 matrix with each ROI having a value. What I want to do is to map the ROI-based measures back to the surface files and show the intensity differences between these 200 ROIs on surfaces. Could someone tell me what is the best way to realize that? Forgive me if this question has bee asked before, but I really do not know how to input best keywords for the question to search in the archive. Many thanks in advance! Leon

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qdec group analysis
by Cat Chong 18 Jun '12

18 Jun '12

Hello Freesurfers, I have created an ROI label for 80 subjects in qdec. My question is the following: Is there a command that will create a .stats file for all my subjects rather than using the below command on each person individually? mris_anatomical_stats -l rh.ento.label \ -t rh.thickness -b -f 4000/stats/rh.ento.stats 4000 rh best regards, Cat

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Editing Putamen Segmentation
by Kristin Javaras 18 Jun '12

18 Jun '12

Dear all, For a number of my participants, Freesurfer's augmented segmentation of the putamen appears to include brain matter that isn't putamen (e.g., see attached images) - this persists across 5-6 slices, on average. I was wondering what people would recommend - should I edit the aseg? Thank you in advance for any advice, Kristin Javaras _______________________________ Kristin N. Javaras, DPhil Waisman Laboratory for Brain Imaging and Behavior University of Wisconsin - Madison 1500 Highland Avenue Madison, WI 53705 Telephone : +1 (608) 890-1407

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Correction for Multiple Comparisons - Sign Question
by mdkruepke＠uwalumni.com 18 Jun '12

18 Jun '12

Freesurfers- When choosing the simulation type does the ending have to match the sim sign? for instance i see examples with --sim mc-z 10000 3 mc-z.pos.3 --sim sign pos or --sim mc-z 10000 3 mc-z.neg.3 --sim sign neg I guess what i am asking is what does the first sign (in the mc-z.(SIGN).3 mean? michael -- Michael D. Kruepke PhD - University of Illinois at Urbana-Champaign BA - Psych - University of Wisconsin-Madison mdkruepke(a)gmail.com (262)-483-7449

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Choosing a Scanning Sequence
by Sullivan, Patrick M. 18 Jun '12

18 Jun '12

Hello, We are working with previously acquired data, so unfortunately we are unable to use the MPRAGE sequence for the current data set. We would like to use T1 images to compute volumetric results. We are using a Philips 3T Achieva, and the sequences received by most participants are a T1-FFE (FLASH in Siemens terms or SPGR in GE terms) and a T1 TFE sequence (I believe this is TurboFLASH in Siemens terms, although I am not fully familiar with it). Are either of these scans appropriate for performing volumetric analysis of grey/white matter using FreeSurfer? Is either scan preferable to the other? Patrick Sullivan Research Assistant, Chapman Lab War Related Illness and Injury Study Center Veteran's Affairs Medical Center Washington, D.C. 20422 (202) 745-8000 (ext 7566)

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Ridiculous story about Freesurfer
by Andrew Dumas 18 Jun '12

18 Jun '12

Did anyone else happen to see this ridiculous story on Gizmodo today? http://gizmodo.com/5919149/your-brain-scan-looks-different-on-mac-and-pc It cites the recent article "The Effects of FreeSurfer Version, Workstation Type, and Macintosh Operating System Version on Anatomical Volume and Cortical Thickness Measurements" as its only source, and then goes on to completely misinterpret it. This sentence (if I had to pick one) is particularly troubling to me: "The finding is completely crazy, and casts doubt over the way many scans—such as CT and MRI—are analyzed in routine practice." Crazy, right? Enjoy... Andrew

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mri_cnr
by Kushal Kapse 18 Jun '12

18 Jun '12

hi fellas, i am trying to run mri_cnr command in freesurfer to compute and see CNR for gray/white/csf.... the command gives following info as help: -bash-3.2$ mri_cnr usage: mri_cnr [options] <surf directory> <vol 1> <vol 2> ... -s <slope fname> <dist in> <dist out> <step in> <step out> i understand that 'surf directory'= subjects 'surf' folder ; but i am not able to figure out what it means by vol1, vol2 and slope fname......it doesnt show any error but just doesnt do anything even if i mention the surf directory to this command..... i checked on freesurfer mail archive, but no info since 2009 about any update on this command..... may someone please give an info if anyone ever used this command thanks kk

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memory allocation error with mris_register for one subject
by Arno Klein 18 Jun '12

18 Jun '12

hello! i am able to run mris_register on all of the OASIS brain images that i have tested except for one: OAS1_0061_MR1: mris_register -curv OASIS-0061_MR1/surf/rh.sphere templates/freesurfer/rh.OASIS_template.tif OASIS-0061_MR1/surf/rh.sphere_to_OASIS_template.reg using smoothwm curvature for final alignment $Id: mris_register.c,v 1.59 2011/03/02 00:04:33 nicks Exp $ $Id: mrisurf.c,v 1.693.2.2 2011/04/27 19:21:05 nicks Exp $ reading surface from OASIS-0061_MR1/surf/rh.sphere... TAGskip: tag=1717658469, failed to calloc 1868656640 bytes! Cannot allocate memory the .sphere files are the same size, but i get a memory error. any idea why this might be? cheers, @rno

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Freesurfer