Hi Pradeep,
is this the result of a single subject? In a single subject lot's of
things can happen (e.g. motion artefacts can affect a single time point,
other imaging or measurement noise will have effects). Also how far are
the time points apart? Run the same thing with 20 subjects and you
should see significantly reduced variablility in the longitudinal stream
vs the cross sectional one.
Best, Martin
On 04/16/2015 01:12 PM, Pradeep wrote:
Hello All,
I have pre-processed a subject that has T1 scans at 3 time points
using the freesurfer cross-sectional and longitudinal methods. The
results show a lot of variability. I have attached the plots. Any
advice would be much appreciated.
Thanks,
Pradeep
On Wed, Apr 15, 2015 at 5:26 PM, Pradeep <tprad...@gmail.com
<mailto:tprad...@gmail.com>> wrote:
Hello All,
I have pre-processed a subject that has T1 scans at 3 time using
the freesurfer cross-sectional and longitudinal methods. The
results show a lot of variability. I have attached the plots. Any
advice would be much appreciated.
Thanks,
Pradeep
On Wed, Jun 4, 2014 at 12:03 PM, Alexandru Hanganu
<al.hang...@yahoo.ca <mailto:al.hang...@yahoo.ca>> wrote:
Thank you very much for your answer Bruce !
have a nice evening,
Alex.
Le 3 juin 14 7:6, Bruce Fischl a écrit :
> Hi Alex
>
> I would think that longitudinal analysis is still the way to
go as we try
> to improve both reliability and sensitivity using the fact
that we have
> multiple scans/subject.
>
> cheers
> Bruce
> On Tue, 3 Jun 2014, Alexandru Hanganu wrote:
>
>> Hello Everyone,
>>
>> could someone please give us an advice about which method
you consider is
>> the best for our study ?
>>
>> we have two groups with MRI at Time 1. Each group received
medication. After
>> this we performed another MRI at Time 2 after 2 weeks.
>>
>> The best method for this study is a longitudinal one or a
cross-sectional
>> GLM ?
>>
>> We consider that the distance between the time points is
too small, and the
>> longitudinal method is not the best choice. Hence, this
study should be
>> treated as a cross-sectional one. In this case we think
about performing a
>> simple GLM with the contrasts:
>> 0.5 0.5 0.5 0.5
>> or 1 -1 -1 1
>>
>> for the groups:
>> 1) grp 1 time 1
>> 2) grp 1 time 2
>> 3) grp 2 time 1
>> 4) grp 2 time 2
>>
>> we are searching to see whether medication had any impact
on the cortical
>> morphology in each group and between the groups.
>>
>> Thank you !
>> Best regards,
>> Alex.
>>
>>
> _______________________________________________
> Freesurfer mailing list
> Freesurfer@nmr.mgh.harvard.edu
<mailto: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 list
Freesurfer@nmr.mgh.harvard.edu
<mailto:Freesurfer@nmr.mgh.harvard.edu>
https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
_______________________________________________
Freesurfer mailing list
Freesurfer@nmr.mgh.harvard.edu
https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
--
Dr. Martin Reuter
Instructor in Neurology
Harvard Medical School
Assistant in Neuroscience
Dept. of Radiology, Massachusetts General Hospital
Dept. of Neurology, Massachusetts General Hospital
Research Affiliate
Computer Science and Artificial Intelligence Lab,
Dept. of Electrical Engineering and Computer Science,
Massachusetts Institute of Technology
A.A.Martinos Center for Biomedical Imaging
149 Thirteenth Street, Suite 2301
Charlestown, MA 02129
Phone: +1-617-724-5652
Email:
mreu...@nmr.mgh.harvard.edu
reu...@mit.edu
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.
