Hi Gwenaelle,
thank you very much for your answer.
My pathological sample is formed by malnourished subjects with anorexia
nervosa. The information in my previous message was partially wrong,
because I have found only a trend towards a decrease in FA, a significant
increase in MD (both L1 and L23) especially in thalamic radiation, fornix,
superior longitudinal fasciculum (more the left).
Now I have run randomise with MO using TBSS, and in the same tracts I have
found a significant decrease in MO (so from linear to planar).
Why did not FA show a significant decrease? is it because in regions of
crossing fibers there can be a difference in degeneration across different
types of fibers (as you hypothesized in your paper on AD/MCI)? how can I
test this or other hypotheses?
Thank you for your help
there are so few examples of the use of MO in the literature!
Angela
> Hi Angela,
>
> you can use the mode of anisotropy as you would use any other DTI indices.
> It proved to be more sensitive than FA in regions of crossing fibres in
> MCI/AD, but it really depends on your own question/population.
>
> You simply need to run tbss_non_FA on the dtifit output images *_MO. If
> they have not been created by dtifit, then you need to update your version
> of FSL.
>
> Cheers,
> Gwenaelle
>
>> De: Angela Favaro <[log in to unmask]>
>> Objet: [FSL] a question about TBSS mode of anisotropy (MO)
>> À: [log in to unmask]
>> Date: Vendredi 15 juillet 2011, 9h23
>> Dear FSL experts,
>> I am performing a study with TBSS.
>> My pathological group did not show significant differences
>> analysing FA
>> (although there are trends between 0.06 and 0.08 TFCE
>> corrected that show
>> decreased FA) or MD, but I have found 4 clusters (more than
>> 100 voxel) of
>> increased L1. In order to better understand this result I
>> have decided to
>> analyse the mode of anisotropy (MO file).
>>
>> My questions are:
>> may I use TBSS to analyse MO?
>> I have read a paper of Gwenaëlle about MCI where a
>> voxel-based approach
>> has been used for MO files. Is this always more correct or
>> it has been
>> used because of the particular population? IN the case of
>> voxel-based
>> analysis, do I need to smooth the images and how much? do I
>> need to use a
>> mask excluding gray matter or do I perform a whole-brain
>> analysis?
>> any help or suggestion is welcome!
>>
>> Angela
>>
>> Angela Favaro, MD, PhD
>> Psychiatric Clinic
>> Department of Neurosciences
>> via Giustiniani 3
>> 35128 Padova
>> Italy
> --------------------------------------------------------------------
>
> Gwenaëlle Douaud, PhD
>
> FMRIB Centre, University of Oxford
> John Radcliffe Hospital, Headington OX3 9DU Oxford UK
>
> Tel: +44 (0) 1865 222 523 Fax: +44 (0) 1865 222 717
>
> www.fmrib.ox.ac.uk/~douaud
>
> --------------------------------------------------------------------
>
>
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