Hi - This has been discussed on this list in the past.
Short answer is: no, there isn't an "optimal" threshold.
We favour use of exclusion/inclusion mask and fairly liberal thresholds in order to select pathways.
Saad
On 24 Aug 2012, at 10:47, Lana VASUNG wrote:
> Hi FSL experts!
>
>
> Can you help me with the choosing the probtrackx treshold.
>
> I have done probtrackx from the ROIs and I have two groups of subjects.
> I would like to use this fiber track as a mask (I need to choose the threshold)
> to calculate the FA values of the track in group A and group B
> and to compare it.
>
> Currently I do not know what is the 'optimal' value to choose
> as a probabilistic track threshold for this fiber output.
>
> Thank you in advance!!
>
> L.
--
Saad Jbabdi
University of Oxford, FMRIB Centre
JR Hospital, Headington, OX3 9DU, UK
(+44)1865-222466 (fax 717)
www.fmrib.ox.ac.uk/~saad
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