the flow_to_tal images are what you need. These encode the direction and amount of cerebral edge flow (=shift) in MNI152 standard space. You can feed these into appropriate statistical analyses. Due to the nature of these images, Gaussian random field prerequisites are violated, i.e. we would recommend a strict Bonferroni correction or a more liberal nonparametric approach (e.g. by using the randomize function which should be in the upcoming release - right, Steve?).
Note that the render image is rendering the individual flow images onto the halfway transform image. These are for visualization purposes only, i.e. you do not really want to do any further analyses on those. However, you could define ROI mask based on these images and apply these masks to the individual flow images in native space. Based on the voxel flow in these masks, you could obtain change values for specific ROIs.
I have not used Jacqueline implementation but Steve or Jacqueline herself may provide further information on this.
Von: Santiago Reig [mailto:[log in to unmask]]
Gesendet: Do 02.09.2004 14:05
An: [log in to unmask]
Betreff: Re: [FSL] Regional quantification using SIENA and SIENAX
Andrea and Steve,
Many thanks to for your suggestions. Iìve made some tests with
siena_flow2tal (it took me a while to figure out that the script needs
some of the output from SIENA first) and now I get a threshold number and
a *_FLOW_DIL and *_FLOW_TO_TAL images that I donìt know how to interpret.
I understand that a posterior voxel-wise analysis is a way to go but I was
thinking of a way to segment directly into ROIìs the
IM1_HALFWAYTO_IM2_RENDER output from SIENA??
On the other hand, the solution of J Chen is really neat: measuring the
atrophy in mm of cortical thickness change. Thatìs a much more practical
result and easy to interpret for a clinician like me. The problem is how
to get those numbers from SIENA output??
Does the script SIENA_FLOW2TAL include anything to do that?
Many thanks in advance!
Santiago Reig, PhD.
Gregorio Maranon Hospital, Universidad Complutense de Madrid
Experimental Surgery and Medicine Lab
Dr. Esquerdo 46, 28007 Madrid, SPAIN
Fax# 34 91 426 5108, Ph# 34 91 426 5067
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