[Mristudio-users] Gradient table

[Seongjin]

Thanks for your comment.

-SC

On Fri, May 8, 2009 at 10:54 AM, susumu <susumu at mri.jhu.edu> wrote:

>  Yes. That's the idea.
>
> One thing you have to be careful is, if you have repeated dataset, like 3
> sets of 12-orientation measurements.
>
> After AIR, each DWI could be rotated in a different way and therefore
> obtain a new gradient orientation.
>
> That means, the 3 repeated measurements may no longer have the same
> 12-orientation gradient table. Instead, you will get 36 orientations.
> Therefore, you have to combine all 3 sets to create one measurement with 36
> orientations and your gradient table also has to be one 36-orientation
> table.
>
>
>
> Is this correct, Hangyi?
>
>
>
> In DtiStudio, you can create average and subtracted images of repeated
> measurements using the "mean, STD" button. From these images, you can get
> idea about how much translation and rotation occurred during the scans.
> Usually, the rotation is very tiny, like within 1 degree. In this case, you
> don't have to use gradient table rotation, in my opinion. Unless you have a
> bad data in which subject was moving more than few degrees, this rotation
> correction may not have much importance. On the other hand, if the subject
> is moving around, you may have other issues like image corruptions and
> motion within one image (odd and even slices are not registered), which can
> not be solved by AIR.
>
>
>
> So, I guess what I'm saying is you should carefully inspect your data,
> instead of just throwing your data into AIR, do gradient table rotation, and
> forget about it.
>
>
>  ------------------------------
>
> *From:* mristudio-users-bounces at mristudio.org [mailto:
> mristudio-users-bounces at mristudio.org] *On Behalf Of *[Seongjin]
> *Sent:* Thursday, April 30, 2009 3:32 PM
> *To:* DTI Studio, ROI Editor, Landmarker Questions/Support
> *Subject:* Re: [Mristudio-users] Gradient table
>
>
>
> After AIR registration (with option modified gradient table if
> available...), I have a new gradient table in AirMatrix.txt file.
> Then I loaded AIR registered image and the new gradient table for tensor
> calculation and tractography.
> Am I doing right?
> Thanks in advance.
>
> -SC
>
> On Thu, Apr 30, 2009 at 1:18 PM, susumu <susumu at mri.jhu.edu> wrote:
>
> The gradient table for Philips scanner calculated by this program is
> "correct", meaning no flipping and other modifications are necessary.
>
>
>
> I strong encourage users to use this program if you are using the
> "overplus" option + oblique slice. You can type in the oblique angles and
> get a recalculated table.
>
>
>  ------------------------------
>
> *From:* mristudio-users-bounces at mristudio.org [mailto:
> mristudio-users-bounces at mristudio.org] *On Behalf Of *[Seongjin]
> *Sent:* Thursday, April 30, 2009 12:28 PM
> *To:* DTI Studio, ROI Editor, Landmarker Questions/Support
> *Subject:* [Mristudio-users] Gradient table
>
>
>
> I appreciate the tutorial session at Queen's Medical Center in Honolulu.
>
> I am using gradient table (for DTI studio ) generated at the following
> link:
> http://godzilla.kennedykrieger.org/~jfarrell/OTHERphilips/GUI.html<http://godzilla.kennedykrieger.org/%7Ejfarrell/OTHERphilips/GUI.html>
>
> I wonder if I can directly use the gradient table from this java applet
> without field flipping.
> Thanks in advance.
>
> -SC
>
>
> _______________________________________________
> Mristudio-users mailing list
> Mristudio-users at mristudio.org
> http://lists.mristudio.org/mailman/listinfo/mristudio-users
>
>
>
> _______________________________________________
> Mristudio-users mailing list
> Mristudio-users at mristudio.org
> http://lists.mristudio.org/mailman/listinfo/mristudio-users
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.mristudio.org/pipermail/mristudio-users/attachments/20090508/5b9fc008/attachment.html