[Mrtrix-discussion] MRtrix gradient table

[Donald Tournier]

Hi Koji,

Seems fine to me. The transform matrix is essentially a 3x3 rotation matrix
(the top-left part), and a translation vector (the right column). You can
ignore the bottom row. This basically says you have a pure axial
acquisition (rotation matrix is identity), with the bottom left pixel in
your image volume centred [ -1.12 -0.26 0.27 ] mm away from the isocentre
of your scanner. Given that this is a small animal system, the fact that
your translation vector is so much smaller than in our example simply
reflects the much smaller FoV in your data.

Cheers,
Donald.


On Mon, Jun 2, 2014 at 7:45 AM, 鎌形康司 <kkamagat at juntendo.ac.jp> wrote:

> Hi,
>
> I have a question about the gradient direction table used in Mrtrix.
> Jones 30 MPG was used, but, in our DWI data. there is no information about
> gradient direction in dicom header.
> Our scanner is *7T* *Bruker* *Scanner* (The *7T* (20 cm bore) small
> *animal* imaging system).
>
> I can check this using mrinfo
> <http://www.brain.org.au/software/mrtrix/commands/mrinfo.html>, but there
> is a some different things between our data and  example in Frequently
> Asked Questions.
>
> *our data*
>
>   Transform:             1           0           0      -1.12
>                                -0           1           0      -0.26
>                                -0          -0           1       0.27
>                                 0           0           0          1
>
> *example data*
>
> Transform:               1           0          -0      -115.4
>                                 0           1          -0      -106.6
>                                -0          -0           1      -7.898
>                                 0           0           0           1
> Is this correct?
>
> --
> Koji Kamagata, MD, PhD
> Department of Radiology, Juntendo University School of Medicine,
> 2–1-1, Hongo Bunkyo-ku Tokyo 113-8421 Japan;
> e-mail: kkamagat at juntendo.ac.jp
>
> _______________________________________________
> Mrtrix-discussion mailing list
> Mrtrix-discussion at www.nitrc.org
> http://www.nitrc.org/mailman/listinfo/mrtrix-discussion
>
>


-- 
*Dr J-Donald Tournier (PhD)*

*Senior Lecturer, **Biomedical Engineering*

*Division of Imaging Sciences & Biomedical EngineeringKing's College London*


*A: Department of Perinatal Imaging & Health, 1st Floor South Wing, St
Thomas' Hospital, London. SE1 7EH*
*T: +44 (0)20 7188 7118 ext 53613*
*W: http://www.kcl.ac.uk/medicine/research/divisions/imaging/departments/biomedengineering
<http://www.kcl.ac.uk/medicine/research/divisions/imaging/departments/biomedengineering>*
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.nitrc.org/pipermail/mrtrix-discussion/attachments/20140602/a6e2e1ff/attachment-0001.html>