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<DIV><FONT face=Arial size=2>Hi all,</FONT></DIV>
<DIV><FONT face=Arial size=2>I'd like to generate ground truths for the purpose
of evaluating brain EPI registration algorithms. I'd like your
feedback and advice about this as well as any resources on the net you may think
are useful to the task.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>1. One approach is to consider a T2 image as a good
proxy for EPI. The challenge then is to create a realistic distortion that
can serve as a synthetic EPI. Obviously the intensity values will not be
quite the same. So the question here is then:</FONT></DIV>
<DIV><FONT face=Arial size=2> 1a) Are the intensity variations
between T2 and EPI close enough to make a warped T2 a good synthetic
EPI?</FONT></DIV>
<DIV><FONT face=Arial size=2> 1b) What is a good approach to create
a realistic warp to transform T2 to EPI?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>2) The second approach is to collect a set of
registered EPI-T2 (or EPI to any other undistorted MRI image) set that human
experts believe are excellent registrations. Then generate a statistical
model for the typical warps that undistort the EPI images. Finally use one
or more corrected (i.e. undistorted/registered) EPI images as ground truth and
apply the synthetic warp to it to get a distorted EPI. The issues here
are:</FONT></DIV>
<DIV><FONT face=Arial size=2> 2a) Is this a sound approach?
What normalization issues should I consider before applying a generic warp field
based on statistics on an undistorted image to produce a synthetic distorted
EPI?</FONT></DIV>
<DIV><FONT face=Arial size=2> 2b) Is there a database of registered
EPI images?</FONT></DIV>
<DIV><FONT face=Arial size=2> 2c) Are the correction warp fields for
those EPI images available and if not, how can I recover it</FONT></DIV>
<DIV><FONT face=Arial size=2> </FONT></DIV>
<DIV><FONT face=Arial size=2>3. I guess I should have asked this first
:) what work has already been done in this area? Are there programs
or databases the provide warped and undistorted EPI ground truths?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Any and all feedback is highly
appreciated.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Arash</FONT></DIV></BODY></HTML>