Hi,
I just attempted to unwarp my DTI data using a gre fieldmap. We're using a
Siemens Allegra 3T. The results look really great from what I can tell !
After unwarping, I see these black signal voids in ventral temporal and
frontal areas that are not visible in the original distorted data. They get
smaller with greater smoothing of the fieldmap. I provide links to some
snapshots
(original b0, unwarped at 0.5mm smoothing, 2.0mm and 4.0mm) at the bottom.
I just want to make sure this is to be expected, and also is there a
recommendation on the
amount of fieldmap smoothing one should do? Should the amount be relative
to the spatial resolution of the data? This data here is 2mm3.
thx
Mark
http://www.princeton.edu/~mpinsk/1.jpg - b0 original
http://www.princeton.edu/~mpinsk/2.jpg - b0 0.5 fm smoothing
http://www.princeton.edu/~mpinsk/3.jpg - b0 2.0 fm smoothing
http://www.princeton.edu/~mpinsk/4.jpg - b0 4.0 fm smoothing
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