[MINC-users] rawtominc & nu_correct difficulties

[Andrew Janke]

The distance parameter is related to field strength.  It should be set
to the distance over which you would expect a typical signal
fluctuation.  This typically amounts to one wavelength.

a

On 8/2/07, Audette, Michel <Michel.Audette at medizin.uni-leipzig.de> wrote:
> The distance issue looks very relevant. This is a very small, high-res volume, with 0.078mm isotropic spacing, so that the longest axis is 38.2mm. Let me try that distance parameter then...
>
> Thanks again,
>
> Michel
>
>
> -----Original Message-----
> From: minc-users-bounces at bic.mni.mcgill.ca on behalf of Andrew Janke
> Sent: Wed 8/1/2007 5:38 PM
> To: MINC users mailing list
> Subject: Re: [MINC-users] rawtominc & nu_correct difficulties
>
> > I can forward to anyone my minc volume, in case someone has an idea what to tweak.
> >
> > Thanks to Andrew, for your suggestion too. I was about to try that next. Do you think that the byte-vs-short issue is responsible for this underestimation?
>
> It it possible as N3 works by minimising the entropy of a histogram.
> It uses a fairly sensitive method to do this so perhaps you are just
> getting a restriction of range effect in the calculation of the
> entropy of the histogram.
>
> It is always worth a try!
>
> Be sure to adjust the distance parameter if you think there is more
> than just base B0 problems in there.  For example for 3T data we
> generally reduce the distance to 50-70mm as opposed to the default.
>
>
>
> a
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-- 
Andrew Janke   (a.janke at gmail.com || http://a.janke.googlepages.com/)
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