Peter Erhard wrote:
>
> Dear Rik, could you please elaborate. See below.
>
> On Wed, 9 Feb 2000, Rik Henson wrote:
>
> >
> > > I tried to use slice timing in spm99 for some fMRI data. I expected slice
> > > timing in spm99b and spm99 to be similar, but they are not! In spm99,
> > > inputs of TR and TA are required, but NOT in spm99b. The version in
> > > spm99b is v2.3 and ,in spm99, v2.6.
> > >
> > > (An earlier post about TA was found in the archive in Sept 99, but
> > > generated only one response/follow-up question.)
> > >
> > > My questions:
> > > 1. What is the acquistion time (TA)? Can someone give an example how
> > > this is determined?
> >
> > In simple terms, the TA is the time between acquisition of the first
> > slice
> > and acquisition of the last slice of one scan, whereas the TR is the
> > time
> > between acquisition of the first slice of one scan and the first slice
> > of
> > the next scan (ie TA<=TR). In some acquisition sequences, there is an
> > appreciable gap between successive scans (TA<TR) which needs to be taken
> > into account in the slice-timing correction.
>
> Is TA not the time between teh start of the first slice and the end of the
> last slice of one scan. That would make more sense to me ??
You're correct - I'm sorry that I didn't spell it out explicitly, but
that is what I meant to imply: START of first slice and END of last
slice.
Rik
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