Hi Saad,
Thank you very much for your help! I've got better understanding of this
issue thanks to your papers. Can I use the ball and stick model using a
gamma distribution of diffusivities with FSL?

Best regards,
Sol

On 18 October 2014 14:05, Saad Jbabdi <[email protected]> wrote:

>  Hi Sol
> I would recommend that you use the b=1000 shell and run dtifit.
> You can extract the b=1000 shell from the data using fslsplit and
> fslmerge. We will soon release a tool (fslselectvols) which should make
> this more straightforward.
>
>  Cheers
> Saad.
>
>
>
>  On 17 Oct 2014, at 15:34, 임솔 <[email protected]> wrote:
>
>  Thank you so much for your helpful replies!
>
>  While waiting for comments from Oxford, what do you recommend for tensor
> fitting?
>
>  Many thanks,
> Sol
>
> On 16 October 2014 18:19, Harms, Michael <[email protected]> wrote:
>
>>
>>  Note though that you'll want to consider whether to use all the shells
>> if computing a standard tensor fit because the assumption of Gaussian
>> diffusion and mono exponential decay starts to break down for b>1500 or so.
>>
>>  Perhaps someone from Oxford will chime in with more detailed thoughts
>> on that issue.
>>
>>  cheers,
>> -MH
>>
>>   --
>> Michael Harms, Ph.D.
>>  -----------------------------------------------------------
>> Conte Center for the Neuroscience of Mental Disorders
>> Washington University School of Medicine
>> Department of Psychiatry, Box 8134
>> 660 South Euclid Ave. Tel: 314-747-6173
>> St. Louis, MO  63110 Email: [email protected]
>>
>>   From: <House>, Matthew House <[email protected]>
>> Date: Thursday, October 16, 2014 12:11 PM
>> To: 임솔 <[email protected]>, "[email protected]" <
>> [email protected]>
>> Subject: Re: [HCP-Users] How I can use grad_dev file for tensor fitting
>> using FSL dtifit?
>>
>>   Hi, Sol.  There is a hidden option of ‘--gradnonlin’ in the dtifit
>> command to enable this function.  Below is an example command that I used
>> in a script to loop over the HCP DTI data.
>>
>>
>>
>> dtifit -k data.nii.gz -r bvecs -b bvals -m nodif_brain_mask.nii.gz -o
>> $OUTDIR/$SUBJECT/dti --gradnonlin=grad_dev.nii.gz
>>
>>
>>
>> ~Matt
>>
>>
>>
>> *From:* [email protected] [
>> mailto:[email protected]
>> <[email protected]>] *On Behalf Of *??
>> *Sent:* Thursday, October 16, 2014 12:06 PM
>> *To:* [email protected]
>> *Subject:* [HCP-Users] How I can use grad_dev file for tensor fitting
>> using FSL dtifit?
>>
>>
>>
>> Dear all,
>>
>>
>>
>> I'm trying to fit the diffusion tensor model using FSL dtifit but I do
>> not know how to include gradient correction using grad_dev file. There is
>> an option flag '-gradadj' in Camino to do it. What would be the
>> equivalent argument for FSL dtifit? Many thanks.
>>
>>
>>
>> Best,
>>
>> Sol
>>
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>
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>  ------------------------------------------------------------------
> Saad Jbabdi, PhD
> MRC Career Development Fellow &
> University Research Lecturer
>
>  FMRIB Centre, University of Oxford,
> John Radcliffe Hospital, Oxford, OX3 9DU, UK.
> tel (+44)1865-222466  (fax 717)
> www.ndcn.ox.ac.uk/team/researchers/saad-jbabdi
>
>
>
>

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