Hi Peter and Andreas,
Thank you. I now clearly understand that for an even number of
slices, Siemens takes the second, fourth, sixth etc slice, then the
first, third, fifth, etc slice.
But I am still not sure how to write that in the slice order file...
there are two ways to write it:
1) '2 4 6... 1 3 5 ...'
or
2) '1 3 5... 0 2 4 ...'
Peter's example shows method #2, but the Feat instructions for a slice
order file say "The first slice is number 1, not 0" which seems to
describe method #1.
Sorry to belabor the issue, I am hoping for full clarity for myself
and those who come upon the same question later.
Dan
On 6/27/07, Andreas Bartsch <[log in to unmask]> wrote:
> Hi,
>
> I think per default Siemens tries to avoid recording the most outer slice last. Thus, for even slice numbers (N=6, for example) the excitation reads:
> 2 4 6 1 3 5
> For odd (N = 5), you get:
> 1 3 5 2 4
> Furthermore, transversal slices are usually recorded feet->head, sagittal slices right->left.
> However, the image numbering may be set to non-default values. You would see that in the protocol entry
> sSliceArray.ucImageNumb... = 0x1
> And you must then check how this all translates into your converted data;)!
> Cheers-
> Andreas
>
> -----Ursprüngliche Nachricht-----
> Von: FSL - FMRIB's Software Library [mailto:[log in to unmask]] Im Auftrag von Peter Fried
> Gesendet: Dienstag, 26. Juni 2007 22:00
> An: [log in to unmask]
> Betreff: Re: [FSL] Slice Order
>
> To the best of my knowledge, yes.
>
> > Hi Peter,
> > Thank you! Does that mean that I was wrong about the Siemens scanner
> > collecting odd slices first, when the total number of slices is even?
> > Dan
> >
> > On 6/26/07, Peter Fried <[log in to unmask]> wrote:
> >> Hi Dan,
> >>
> >> I ran into the same problem when I started. You'll want to create a
> >> text file that reads {1, 3, 5, ..., 0, 2, 4, ...} (each number on a
> >> new line).
> >>
> >> This is fsl-speak for {2, 4, 6, ..., 1, 3, 5, ...}, which is the
> >> interleaved order for an even number of Siemens' slices.
> >>
> >> I'll attach the version I use for a 34-slice acquisition on a Siemens.
> >> Note that it is a slice-order file, not a slice-timing file as the
> >> name suggests.
> >>
> >> -Pete
> >>
> >> > Hello,
> >> > I am not sure which slice order option to use. We use a Siemens
> >> > 3T,
> >> and
> >> > collect an even number of
> >> > slices; my understanding is that in this situation the odd slices
> >> > are collected first.
> >> > The interleaved option "0 2 4... 1 3 5" looks like it is even
> >> > numbers first, but in the instructions for making a slice order
> >> > file, it says the first slice should be 1, not zero...so perhaps
> >> > the interleaved option is really doing odd slices first (ie, '0 2
> >> > 4' refers to the
> >> first,
> >> > third and fifth slice)? Is using a slice order text file that says
> >> > "1 3 5 ... 2 4 6..." the same as using
> >> the
> >> > interleaved option?
> >> > Thanks,
> >> > Dan
> >> >
> >>
> >>
> >
>
