Hi,
I'm looking confirm my fieldmap acquisition process and data preprocessing
steps.
My plan is to acquire two distinct GRE field maps with differing echo times
using our 8Ch head coil. I have a couple questions specific to my GE CV's
and a couple more generic questions.
My GE CV's are
rhrcctrl = 15 (for magnitude, phase, real, imaginary, )
autolock = 1
Do I need the raw p-file, if so, for what?
nograd = 1
Should this be set to match the acquisition I'm correcting with the
fieldmap? Ie, if my DTI acqusition has gradwarp, I should be acquiring my
fieldmap with gradwarp also? Or is the opposite true?
saveinter = 1
If i'm processing the data in FUGUE do i need the intermediate files, ie
independent coil element (real, imaginary, mag and phase) images. I didn't
think I but i read in another post (014548) that these could be used.
Also, I read in another post (014548) that it may be preferable to switch to
the headcoil to acquire fieldmaps, this relates to my saveinter question
above, but is this only if i'm processing the fieldmaps using Bernstein MRM,
1994 method? Can I process my 8ch data through FUGUE?
I think what has led to confusion is I have began to process some
preliminary data. When I apply fslinfo to my data I get:
data_type INT16
dim1 256
dim2 256
dim3 4
dim4 1
datatype 4
pixdim1 0.9375000000
pixdim2 0.9375000000
pixdim3 4.0000000000
pixdim4 1.0000000000
cal_max 0.0000
cal_min 0.0000
file_type NIFTI-1+
That is, my datatype isn't 32 (as for complex images)
I am using dcm2nii GUI to convert my .dcm images to .nii.gz, that should be
ok, right?
From my acquisition with the above parameters I have 4 images per slice (as
per my rhrcctrl vaules). The 1st and 3rd images range from 0- about 3140
(this is pi *1000), and it looks quite like a normal MR image, my 2nd image
looks like a badly tuned TV and my 4th image is blank, though i did acquire
the images on a phantom.
Does this sound OK for processing through FUGUE?
Apologies for posting on fieldmaps, I know this has been pretty well
convered but I think I can't see the wood for the trees.
Many thanks
John
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