Dear Payal,
in that case, your TR will be indeed 16 seconds. What is then the "gap"
for auditive stimulus presentation you are talking about in the other
posting? The choice of microtime resolution is up to you, the time bin
you pick as microtime onset should span the time during TR when your
reference slice was acquired. This is usually easiest to figure out
when there is a simple relationship between microtime resolution and
number of slices (e.g. 8 time bins = each time bin covers acquisition
time of 2 slices, 16 time bins = one time bin per slice, 32 time bins =
2 time bins per slice, pick one of them).
Hope this helps
Volkmar
Am Dienstag, den 02.10.2018, 10:01 -0400 schrieb Payal Arya:
> Hi Volkmar
>
> Thanks for your reply.
>
> The whole 3D acquisition (one whole volume of 16 slices) lasts 16
> seconds. It is a RARE (Rapid Acquisition with Refocused Echoes)factor
> 8 pulse sequence where TR is 2 seconds but there are echo pulses.
> There is no gap. I have attached the method file that Bruker system
> generates for each scan. What i thought that it takes16 seconds to
> finish one whole volume so i should be using TR as 16 seconds and TA
> would be 16sec*(1-1/#slices) for slice timing correction. The slices
> are acquired interleaved from bottom to up and i used middle
> slice(slice #7) for reference slice.For first level analysis i kept
> TR as 16 but i could not understand what i should be using for
> microtime onset and resolution. How do i decide on the time bins?
>
> Please correct me if i am wrong in using the above settings.
>
> I appreciate your help.
>
> Thank you
>
> Best
>
> Payal
>
> On Tue, Oct 2, 2018 at 4:06 AM Volkmar Glauche <volkmar.glauche@unikl
> inik-freiburg.de> wrote:
> > Dear Payal,
> > if I understand your various posts to the mailing list correctly, a
> > single 3D acquisition lasts for 2 seconds, with another 14 seconds
> > "gap" before the next 3D acquisition. Slice timing needs to be told
> > about this, and it therefore asks for two time values. For slice
> > timing, TR is the time between acquisition of the 1st slice of scan
> > N and the 1st slice of scan N+1. In your case, this would be 16
> > seconds. TA is the time between acquisition of the 1st slice of a
> > scan and the last slice of a scan. If I got you correctly, it would
> > be 2sec*(1-1/#slices).
> > In 1st level statistics, there is no distinction between TR and TA.
> > TR would be 16 seconds, and you should use the 1st time bin
> > (reference slice/microtime onset = 1) in order to model hrf
> > correctly.
> > Hope this helps
> > Volkmar
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