mriconvert: MRIConvert-2.0.7-win32 _ Warning messages?

[Alshikho, Mohamad J.]

Hi Jolinda,
Thank you very much for your answer! what I want to say is that my data is from Syngo baseline vb 15. Regarding the www.cabiatl.com/mricro/mricron/bvec.doc I was unable to open it. I highly appreciate if you can send me this document
again

Bests,
Mohamad

________________________________________
From: mriconvert-bounces at lists.uoregon.edu [mriconvert-bounces at lists.uoregon.edu] on behalf of Jolinda Smith [jolinda at uoregon.edu]
Sent: Tuesday, November 11, 2014 6:04 PM
To: MRIConvert user's list
Subject: Re: mriconvert: MRIConvert-2.0.7-win32 _ Warning messages?

If your data is from syngo baseline vb15, the polarity of the bvecs might be wrong (and it's a VB15 thing, not an MRIConvert bug). This is probably completely inconsequential, fortunately. Changing the sign on the bvecs doesn't affect any analysis as far as I know, but if you are doing the analysis you'll want to be sure that's true. For the VB13 error, it might be related to this:

The diffusion vector data in Siemen's DICOM header are 'back' calculated from the b-matrix. Prior to VB17 this could in some occasions lead to a 'wrong' inverse solution. It has been fixed from VB17 on. Small differences between the Siemens solution and the other software are due to the fact that Siemens accounts for the impact of the imaging gradients on the effective b-matrix. Thus, anything stored in the DICOM header from VB17 on should be authorative and the best available solution.

The document www.cabiatl.com/mricro/mricron/bvec.doc has suggestions for how to check that the bvecs are correct.

Jolinda

On Tue, 11 Nov 2014 12:28:16 -0800, Alshikho, Mohamad J. <MALSHIKHO at mgh.harvard.edu> wrote:

> Hi ,
> I was using MRI Convert to convert my DICOMs in to NIFI files when I got
> these warning message:
> 1. "Polarity of the bvecs may be wrong for vb15 data"
> 2. "bvecs are sometimes wrong for vb13 data, due to a bug in the
> algorithm by which Siemen's converted the B_matrix to a principle
> eigendirection. use with caution"
>
> Kindly, What is the meaning of each of the previous messages? and if it is BUGs how can I deal with this problem?
>
>
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--
Jolinda Smith, Ph.D.
MR Physicist
Lewis Center for Neuroimaging
University of Oregon
Eugene, OR USA
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