Re: [Freesurfer] longitudinal template generation with manual registration

2014-04-10 Thread Martin Reuter

Hi Andreas,

It is extremely different to get good registrations manually (as you 
have to work in 3D and you only see 2D planes), and you'll most 
certainly not be able to achieve the accuracy of an automated method 
(especially not of robust_register/robust_template, which are pretty 
damn accurate, if you ask me :-). So I strongly advise against that 
(unless you want to show that manual registration messes things up).


Now to answer your question: You could theoretically use 
mri_robust_template to construct the template from your three inputs. 
Then stop the stream, mri_concatenate_lta your transform from image_i to 
image_0 with the transform that roubst_template gives you from image_0 
to template. Then reconstruct the template using mri_robust_template 
with --ixform (passing these transforms) and --noit to not iterate, this 
will recreate the median template image.
Also replace the lta files in the base/mri/transforms with the new ones 
that you got from the concatenation, so that the base and later the long 
streams know.

Resume the recon-all stream.

This, obviously, has never been tested and requires some looking into 
recon-all to make sure you do things right. E.g. you need to use the 
norm.mgz of the inputs and make sure you overwrite the norm_template or 
similar (the one that get's created in the base step).


Best, Martin


On 04/09/2014 05:35 AM, Andreas Werner wrote:

Dear Experts,
i am analyzing a longitudinal study (three timepoints for each 
participant).
I manually register the second and third timepoint to the first 
timepoint using freeview.
Question: Is it possible to use these manually created transformation 
matrices to create a common template that is equidistant from all 
three timepoints to balance interpolation ? If so, which commands do I 
need to use ?
(As I understand  mri_robust_template  does this, but I would like 
to use manual rather than automatic registration.)

Many thanks in advance!
Andreas


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Martin Reuter, Ph.D.

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
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Phone: +1-617-724-5652
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[Freesurfer] longitudinal template generation with manual registration

2014-04-09 Thread Andreas Werner
Dear Experts,



i am analyzing a longitudinal study (three timepoints for each participant).

I manually register the second and third timepoint to the first timepoint using freeview.

Question: Is it possible to use these manually created transformation matrices to create a common template that is equidistant from all three timepoints to balance interpolation ? If so, which commands do I need to use ?

(As I understand  mri_robust_template  does this, but I would like to use manual rather than automatic registration.)

Many thanks in advance!

Andreas
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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.