Dear experts, Could anyone please help me ? My group has small size (7 subjects) with non equally spaced different timepoints (from 2 up to 4).
Best regards, Matthieu Le 30 sept. 2015 13:57, "Matthieu Vanhoutte" <matthieuvanhou...@gmail.com> a écrit : > Hi Martin, > > Thank you for helping ! > > 1) What should I use for the parameter estimation: "mass univariate" or Novel > mass-univariate tools (spatiotemporal models)" ? > > 2) I have one group of subjects with different timepoints (non equally > spaced and different numbers of timepoints), and would like to see the > significant change of FA according to time. Will LME study allow me to get > this change and how to define contrast to assess it ? Are the results of > this longitudinal study directionals, i.e. is it possible to establish an > increase or decrease of FA in significant regions according to time ? > > 3) Should the covariates (age, gender...) be demeaned or centered ? > > 4) Has the accurate time variable to be in years absolutely or could it > be also in days ? > > > Best regards, > > Matthieu > > > 2015-09-29 17:11 GMT+02:00 Martin Reuter <mreu...@nmr.mgh.harvard.edu>: > >> Hi Matthieu, >> >> use lme_mass_fit_vw and the y is a simple vector. I would mask the image >> before doing this and only pass the brain voxels (to increase speed and >> reduce comparisons). >> >> Best, Martin >> >> >> On 09/29/2015 10:43 AM, Matthieu Vanhoutte wrote: >> >> Hi Martin, >> >> I understand for the multiple comparisons problem. But if I consider a >> voxel-by-voxel analysis just as hippocampal volume (lme_fit_FS for >> estimation), how could I consider a correction for multiple comparisons in >> this univariate case ? >> >> Shouldn't I use the lme_mass_fit or lme_mass_fit_vw functions in my mass >> univariate case ? If yes, how do I have to format my 3D FA volume as input >> of the LME toolbox ? >> >> Best regards, >> >> Matthieu >> >> ------------------------------------- >> Matthieu Vanhoutte, MSc >> Research Engineer - Department of Neuroradiology >> Regional University Hospital, Lille, France >> >> 2015-09-29 16:34 GMT+02:00 Martin Reuter <mreu...@nmr.mgh.harvard.edu>: >> >>> Hi Matthieu, >>> >>> yes, multiple comparisons are a problem for any mass univariate >>> approach. You can use the FDR2 correction (in the lme matlab tools) which >>> is less conservative than standard FDR. You can also work in specific ROI's >>> and average there, to reduce the number of comparisons. >>> >>> Best, Martin >>> >>> >>> On 09/29/2015 09:11 AM, Matthieu Vanhoutte wrote: >>> >>> Hi Martin, >>> >>> Thank you for your answer. >>> >>> However, I would like to consider FA maps as a mass-univariate problem >>> and not a univariate voxel-by-voxel as hippocampal volume. Indeed, my >>> voxels aren't independant, are they ? So, how to correct for multiple >>> comparisons then ? >>> >>> Best regards, >>> >>> Matthieu >>> >>> 2015-09-29 15:04 GMT+02:00 Martin Reuter <mreu...@nmr.mgh.harvard.edu>: >>> >>>> Hi Matthieu, >>>> >>>> if all your images are perfectly registered, you can do LME on a >>>> voxel-by-voxel basis, just as if you had hippocampal volume or any other >>>> ROI measure. >>>> >>>> Best, Martin >>>> >>>> >>>> On 09/29/2015 06:46 AM, Matthieu Vanhoutte wrote: >>>> >>>> Dear experts, >>>> >>>> I would like to know if it is possible to make a longitudinal study >>>> with LME toolbox from volume FA maps registered in a common space ? >>>> >>>> I don't have T1 images so the recon-all process couldn't be processed. >>>> But if I put my 3D FA volume of dim = [nx,ny,nz] in a 1D nx*ny*nz voxels >>>> format, could it be in good way for LME ? >>>> >>>> Thanks for helping ! >>>> >>>> Best regards, >>>> >>>> Matthieu >>>> >>>> >>>> _______________________________________________ >>>> Freesurfer mailing >>>> listfreesur...@nmr.mgh.harvard.eduhttps://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer >>>> >>>> >>>> -- >>>> Martin Reuter, PhD >>>> Assistant Professor of Radiology, Harvard Medical School >>>> Assistant Professor of Neurology, Harvard Medical School >>>> A.A.Martinos Center for Biomedical Imaging >>>> Massachusetts General Hospital >>>> Research Affiliate, CSAIL, MIT >>>> Phone: +1-617-724-5652 >>>> Web : http://reuter.mit.edu >>>> >>>> >>>> _______________________________________________ >>>> Freesurfer mailing list >>>> Freesurfer@nmr.mgh.harvard.edu >>>> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer >>>> >>>> >>>> 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. >>>> >>>> >>> >>> >>> _______________________________________________ >>> Freesurfer mailing >>> listfreesur...@nmr.mgh.harvard.eduhttps://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer >>> >>> >>> -- >>> Martin Reuter, PhD >>> Assistant Professor of Radiology, Harvard Medical School >>> Assistant Professor of Neurology, Harvard Medical School >>> A.A.Martinos Center for Biomedical Imaging >>> Massachusetts General Hospital >>> Research Affiliate, CSAIL, MIT >>> Phone: +1-617-724-5652 >>> Web : http://reuter.mit.edu >>> >>> >>> _______________________________________________ >>> Freesurfer mailing list >>> Freesurfer@nmr.mgh.harvard.edu >>> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer >>> >>> >>> 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. >>> >>> >> >> >> _______________________________________________ >> Freesurfer mailing >> listfreesur...@nmr.mgh.harvard.eduhttps://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer >> >> >> -- >> Martin Reuter, PhD >> Assistant Professor of Radiology, Harvard Medical School >> Assistant Professor of Neurology, Harvard Medical School >> A.A.Martinos Center for Biomedical Imaging >> Massachusetts General Hospital >> Research Affiliate, CSAIL, MIT >> Phone: +1-617-724-5652 >> Web : http://reuter.mit.edu >> >> >> _______________________________________________ >> Freesurfer mailing list >> Freesurfer@nmr.mgh.harvard.edu >> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer >> >> >> 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. >> >> >
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