Hi Katie,
On 12 Jan 2007, at 21:00, Katie Martucci wrote:
> Thanks for the info about copes 5 & 6 - those seem fine then since
> cope 6 is always fully lit-up and
> cope 5 isn't.
Looking at the perfusion manual page (to remind myself of the wizard
setup..)
http://www.fmrib.ox.ac.uk/fsl/feat5/perfusion.html
Note that if you've got control and tag the right way round then it
should be cope 5 that is strongly lit up, not 6 - note the sentence
telling you to change the phase in this case.
This isn't a problem, it just means in your case that you would
expect to see the perfusion activation in cope2 not cope1. (But you'd
still expect to see the BOLD in cope3)
> I'm not sure if it might be just a sensitivity issue then, but a
> lot of the image sets (170 volumes) did
> not show activation in copes 1 & 2.
That probably means that the perfusion activation is just too weak.
You should load the filtered_func_data and stats/zstat2 (the
unthresholded zstat) into FSLView to see if there is _any_ weak
activation, and also look at the timecourses and fitted model plots
at some of the stronger voxels, to get a feel for whether the timing
is maybe way off.
> The majority have act/deact in copes 3 & 4 but not all.
This means that you do have BOLD signal in your data, as well as
(weaker) perfusion activation. Some perfusion acquisitions end up
with some BOLD signal, others have very little.
> The
> second level analysis results had some perfusion activations in
> only 3/11 subjects, perfusion
> deactivations in 2/11, and bold detections in all of them (act. and
> deact.).
>
> We got a lot more when we used the data in a normal feat analysis
> set-up done separately for
> perfusion and bold-is there a reason why this would make sense?
Not sure - what do you mean by separate - i.e., what exactly were
those analyses?
Cheers.
>
> Thanks,
> Katie
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Stephen M. Smith, Professor of Biomedical Engineering
Associate Director, Oxford University FMRIB Centre
FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
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