Hi David,
There is no need to average the volumes acquired with the same diffusion
gradient direction.
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: [log in to unmask]
On 5/1/13 6:08 AM, "David Soto" <[log in to unmask]> wrote:
>hi,
>
>Apologies for this naive question on DTI preprocessing
>
>Difusion data was acquired on a Siemens Verio with 30 directions
>I used MRIconverter to get the .nii and the bvals and bvecs
>Looking in FSLview I see that the initial 3 are non-diffusion, followed
>by what it appears 3 consecutive diffusion scans in direction1, 3
>consective in direction 2.........and likewise up to direction 30
>
>The bvecs output is pasted below.
>
> I gather that I need to average the images number 456 , 789, and so on
>to get an 'average' image for each diffusion direction.
>I can do this using fslroi and fslmaths. Then use fslmerge to concatenate
>them?
>
>could you please let me know if am wrong? do I need to do this
>'averaging' at all? many thanks!
>
>
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>-0.848186 -0.848186 -0.721323 -0.721323 -0.721323 -0.392985 -0.392985 -0.3
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>1
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>6922 0.516922 0.0805979 0.0805979 0.0805979 0.465383 0.465383 0.465383 0.6
>44223 0.644223 0.644223 0.289128 0.289128 0.289128 0.532602 0.532602 0.532
>602 0.765622 0.765622 0.765622 -0.951135 -0.951135 -0.951135 0.956283 0.95
>6283 0.956283 0.178987 0.178987 0.178987 0.0556195 0.0556195 0.0556195 -0.
>314058 -0.314058 -0.314058 -0.576289 -0.576289 -0.576289 -0.653619 -0.6536
>19 -0.653619 -0.458196 -0.458196 -0.458196 -0.074389 -0.074389 -0.074389 0
>.48622 0.48622 0.48622 0.104339 0.104339 0.104339
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