Hi Markus,
I work with Philips Achieva and have good experiences with it. I always use
bvecs and bvals produces by MRIcron, when I do dicom to nifti conversion. I
would guess that the physicist gave you a one single gradient table which I
suppose you use as is. The fact is that the table has to be corrected
(rotated) for imaging slice angulation. MRIcron does it automatically for
you.
So I would suggest you to use MRIcron, and its simple GUI, dcm2nii to convert
from dicom to nifti, and use also bvecs and bvals. I am almost sure that you
will get correct results.
Best,
Martin
On Sunday 05 April 2009 20:58:55 Markus Gschwind wrote:
> Dear DTI experts!
>
> For some month now, I am doing successful FDTing, mostly with Data from
> several Siemens Trio.
>
> Here I got data from a Philips Achiva. Unlike with data from the Siemens
> scanner, here the bvecs and bvals are not recreated by MRIConvert. But I
> got them from the Physicist.
>
> However, I have the feeling that that data are not good, but I am unable to
> say in what.
> In a previous message Saad described how to check for not correct bvecs and
> to correct them.
>
> I have not found that these bvecs are really grossly wrong (correct colors,
> more or less nearly corect lines). I also tried to invert the signs, but it
> was not visible to me if there was an improvement.
>
> However the dti_FA has a lot more noisy high intensity voxels and
> fibertrackging looks quite strange (see attachment).
>
> Would someone mind having a short look at that data? Could I upload them?
>
> Thank you so much!
> Markus
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