Hi all,
I acquired DTI images at a GE-3T using a standard coil as well as an
8-channel coil (using ASSET). I then converted the respective dicoms into
nifti using dcm2nii thus producing the respective the nifti files as well as
the bvals and bvecs. dtifit produced the fa and V1 files that were different
for each coil(see attached). The standard coil vectors seem to be in the
correct orientation but the multichannel coil vectors seem interchanged
between x and y ( red and green). The bvecs were the same for the two. Upon
looking at the dicom headers i found that the standard coil data was
acquired with 'In-plane phase encoding direction' as COL (y direction i
guess) and 'In-plane phase encoding direction' as ROW ( x direction) which
might explain the flip. So should i correct for this by simply exchanging
the x and y vectors in bvecs?
I also acquired 4 b0 volumes. but i found that all 4 are acquired at the
start of the scan. Doesnt this defeat the purpose of acquiring multiple b0?
I thought these have to be interleaved between different gradient
directions. How can i do this on a GE Discovery -750 3T magnet?
Also, i would appreciate any advice on using multichannel coil for dti. As
in, is it better than standard coil for SNR, distortion etc. Thanks!
-Vish
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