Thanks Steve. I have used the Model Wizard; I apologize for the simple
question. But even now, when I run it again using the Wizard (rather than
perfusion subtraction), it does not seem to give me reasonable output. With
perfusion subtraction, I clearly get a very good fit; not the case when
using the full model. I have a TE of 3ms, and therefore should have
negligible a BOLD component, but this does not seem to be the result of the
full model. I then have to wonder whether:
1) I'm somehow misusing the Full Model, even with the wizard.
2) I'm mis-interpreting the output.
3) There's a more fundamental issue with my data.
I've uploaded images (152682) to illustrate the issue... Is this what a
problem with structured noise would look like (i.e. reason to stick to
perfusion subtraction)?
Thanks so much,
Nikki
On Sun, 7 Jun 2009 07:58:36 +0100, Steve Smith <[log in to unmask]> wrote:
>HI - have you tried using the model Wizard, as suggested in the
>manual? This will do the basic setup for you.
>Steve.
>
>
>On 5 Jun 2009, at 19:03, Nicole Pelot wrote:
>
>> Hi,
>>
>> I have read the FEAT Perfusion documentation quite a few times now,
>> but I
>> still cannot figure out how to properly set up my EVs. I have a
>> block design
>> task: 56s/block, 7 blocks, alternating between rest and active
>> (start &
>> finish with rest).
>>
>> My main issue is with EV1. It clearly states that we should be
>> modeling
>> *rest* times, but that leads me to think of a block design with 0's
>> for
>> active and 1's for rest. However, the sample design seems to show
>> all 1's
>> for EV1. Also, what convolution should be applied? None?
>>
>> I've structured EV2 as I always do to correspond to my block design.
>> (On:
>> 56s; Off: 56s; Convolution: Double gamma).
>>
>> EV3, I chose "Interaction", and I made the mean of EV1 zero (but the
>> min of
>> EV2).
>>
>> Thank you,
>>
>> Nicole
>>
>
>
>---------------------------------------------------------------------------
>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)
>[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
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