[Mristudio-users] theory - registration

[Hangyi Jiang]

hi, 

for Yue's method, clicking "Optional parameters" in pixel rejection option, then a parameter dialog will pup up... clicking OK....
otherwise, the outlier pixel rejection uses default parameters.

it is a good question about difference between "theory - registration" and "normal AIR" (in the "image" tab)
basically,   "normal AIR" will register ALL target images to a single user-selected reference image (usually a B0, or mean B0s).  BEFORE tensor calculation.  on the other hand, "theory - registration" do registration for each DWI INDIVIDUALLY with its theory-one iteratively DURING tensor calculation.  in this procedure, the original images are not being changed.   usually, AIR can do a better job if both the reference and target are in similar modality and intensity. from this point of view, "individual" registration during tensor calculation should be better than "normal AIR" before tensor calculation.  however, this method may result in mis-alignment between different DWIs, since the registration is carried out for every single-pair (original and theory one) images, not for all DWIs.

so it is hard to say which method is better.  as my opinion, if the the mis-alignment between the DWIs is a dominant artifact, then "normal AIR" before tensor calculation is recommended.  otherwise,   "theory - registration" during tensor calculation is a good choice.  

regards, 

hangyi




________________________________________
From: mristudio-users-bounces at mristudio.org [mristudio-users-bounces at mristudio.org] On Behalf Of Darren Gitelman [d-gitelman at northwestern.edu]
Sent: Tuesday, May 18, 2010 3:15 AM
To: mristudio-users
Subject: Re: [Mristudio-users] theory - registration

Dear Susumu

I am using the latest 64 bit version that I can download- 3.0.2 (Mar 2010).

When I click pixel rejection, there is no dialog that says Yue's
method, yes | no. There is just a button that says optional
parameters. I filled in 30 for the min bad area, 3 for the min z value
and 50 for the min B0- value. Then I clicked binary mask. Then OK to
the options dialog. Then OK to the DTI-Map Options dialog. The
calculation starts, but again the X appear on the slices and there is
no binary pixel mask.

While I'm at it I have some other questions about theory - registration

1) Should I run other registration methods such as AIR or MI before
theory-registratin? Will theory-registration take care of eddy current
correction?

2) What images are changed by theory registration?  The original
images? It doesn't seem to produce new images such as with mutual
information or AIR.

Thanks,
Darren
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