I understand acquiring 2x the data is not always possible for phase up/phase
down, but a field map takes 2 minutes on a Siemens Trio (and can't take much
longer on another scanner). In my opinion, there isn't ever a good reason
not to acquire a field map if you are acquiring EPI.
Peace,
Matt
-----Original Message-----
From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On Behalf
Of Martin Kavec
Sent: Tuesday, April 20, 2010 1:30 AM
To: [log in to unmask]
Subject: Re: [FSL] AW: [FSL] EPI distortion of DTI
Hi Jesper,
it was not possible for me to keep my patients in the magnet for extended
periods that's why I am also left with approach discussed in this thread.
On Monday 19 April 2010 22:24:30 you wrote:
> This means that one can often see
> that fnirt attempts to "widen" these tracts, which I think might be
> quite bad in many applications.
>
Disregarding the important issues discussed later in this thread I wonder,
whether you haven't tried segmenting WM from T1, skeletonize both the FA nad
T1-WM and FNIRT them. This way you would work on the centers of the track in
the both images and may avoid the widening.
Thanks,
Martin
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